WCAT Decision Number:  
A2100606 (August 17, 2022)  
DECISION OF THE WORKERS’ COMPENSATION APPEAL TRIBUNAL  
WCAT Decision Number:  
A2100606  
WCAT Decision Date:  
August 17, 2022  
Introduction  
[1]  
[2]  
[3]  
This appeal arises out of a Review Division decision dated February 23, 2021, whereby the  
worker’s request for review was denied. In that decision, a review officer at the Workers’  
Compensation Board (Board)1 confirmed a prior decision of the Board dated June 1, 2020. The  
review officer denied the worker’s claim for carbon monoxide poisoning and a uterine fibroid as  
occupational diseases due to the nature of her employment.  
The worker now appeals the February 23, 2021 Review Division decision to the Workers’  
Compensation Appeal Tribunal (WCAT). The appeal proceeded by way of an oral hearing,  
which took place via videoconference on October 26, 2021. The worker represented herself in  
the appeal. The employer participated in the appeal and was represented by an employers’  
adviser.  
On appeal, the worker argued that beginning in the fall of 2017, she was exposed to  
carbon monoxide and other toxic airborne substances/heavy metals at work. As a result of this  
exposure, she suffered from carbon monoxide poisoning. She also developed a uterine fibroid  
and experienced miscarriages thereafter. The worker requested that I vary the review officer’s  
decision by allowing her claim for carbon monoxide poisoning as well as her uterine fibroid and  
subsequent miscarriages as occupational diseases due to the nature of her employment.  
[4]  
[5]  
On the other hand, the employer argued that there was insufficient evidence to support that the  
worker suffered from carbon monoxide poisoning, or that she was exposed to any other toxic  
levels of airborne substances/heavy metals that would have caused her uterine fibroid and/or  
miscarriages. The employer requested that I deny the worker’s appeal and confirm the review  
officer’s decision.  
Preliminary Matters  
At the hearing, the worker noted that she had all along argued that in addition to her exposure to  
carbon monoxide, she was also exposed to other toxic substances/heavy metals that caused  
her uterine fibroid and miscarriages. Despite this, the Board did not specifically address her  
miscarriages. She requested that I adjudicate the compensability of her miscarriages in my  
1
operating as WorkSafeBC  
1
150, 4600 Jacombs Road, Richmond, B.C. V6V 3B1  
Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
decision. The employer argued that the review officer did not specifically consider the  
compensability of the worker’s miscarriages. As a result, I did not have the jurisdiction to  
consider that matter.  
[6]  
In the underlying June 1, 2020 Board decision on appeal, the case manager addressed the  
worker’s evidence about her reproductive issues/miscarriages. However, the claim was  
ultimately denied for carbon monoxide poisoning and the uterine fibroid. As a result, the case  
manager determined that no compensable consequences arising out of those injuries  
(and therefore the miscarriages) were compensable. In these circumstances, I am satisfied that  
the compensability of the worker’s miscarriages formed a part of the broader adjudication of the  
worker’s entitlement for claim acceptance of an occupational disease(s). As such, I find that I  
have the requisite jurisdiction to consider the worker’s miscarriages in my decision.  
[7]  
On a separate matter, I note that since the start of the claim in 2018, both parties have provided  
extensive evidence to the Board, Review Division, and WCAT. I have not recounted all of the  
evidence or the parties’ submissions, but I have read and considered them in their entirety.  
Some of the worker’s evidence/submissions pertained to her concerns about how the employer  
handled her complaints and its investigation in general, as well as other labour relations issues  
about her reassignment offer in 2018. These matters do not fall within my jurisdiction to consider  
in the context of the current appeal. As such, I have not addressed these aspects of the  
worker’s evidence/submissions in detail.  
Issue(s)  
[8]  
The issues on appeal are:  
1. Did the worker suffer from carbon monoxide poisoning as an occupational disease due to  
the nature of her employment?  
2. Are the worker’s uterine fibroid and/or miscarriages in 2018 occupational diseases due to  
the nature of her employment?  
Jurisdiction and Standard of Proof  
[9]  
This appeal is brought under section 288(1) of the Workers Compensation Act (Act),2 which  
permits appeals of Review Division decisions to WCAT.  
[10]  
WCAT has exclusive jurisdiction to inquire into, hear, and determine all those matters and  
questions of fact, law, and discretion arising or required to be determined in an appeal before it  
(section 308 of the Act). It is not bound by legal precedent (section 303(1) of the Act).  
2
All references to the Act in this decision refer to the Workers Compensation Act, RSBC 2019, c 1.  
2
150, 4600 Jacombs Road, Richmond, B.C. V6V 3B1  
Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
[11]  
The standard of proof is the balance of probabilities as modified by section 303(5) of the Act.  
That section provides that in compensation cases where the evidence supporting different  
findings on an issue is evenly weighted, WCAT must resolve that issue in a manner that favours  
the worker.  
Background and Evidence  
[12]  
[13]  
The worker was a high school industrial technology teacher. She started working at a new  
school in 2016.  
There were several welding processes that took place in the worker’s metal shop classroom  
including millwork, shielded metal arc welding, plasma welding, casting, and oxy-acetylene  
cutting. A foundry was also set up in the shop. It had a canopy local exhaust system, as did  
2 benches that were set up for welding work. The dimensions of the metal shop were  
approximately 100 feet x 60 feet, with a 20-foot high ceiling (120,000 cubic feet).  
[14]  
[15]  
In the summer of 2017, the employer upgraded the school’s entire ventilation system, which  
included replacing the fume extraction system in the metal shop.  
In October 2017, during the installation of a new heating, ventilation, and air conditioning  
(HVAC) unit, a contractor noted that the metal shop fume extractor was not working properly.  
There was a loose belt and the electrical breaker for the exhaust fan was locking out. A work  
request for repair was submitted on October 2, 2017, which was completed without delay.  
[16]  
[17]  
In an email to a school administrator dated November 3, 2017, the worker requested carbon  
monoxide detectors for the metal shop. She felt there was lack of ventilation in the classroom  
when all the equipment was being used. Although she was told that the HVAC unit was working,  
by lunchtime she was getting “major migraines” and felt like “puking.”  
On November 3, November 29, and December 6, 2017, the employer received complaints from  
staff about the school’s indoor air quality with reports of headaches, nausea, exhaustion, and  
facial erythema. According to an employer’s investigation report, the worker reported that since  
late October/early November 2017, she experienced headaches, nausea, and exhaustion when  
all the welding equipment was running in the metal shop.  
[18]  
In an email to the school principal dated November 30, 2017, the employer’s occupational  
health and safety manager (OHS manager) noted that it was possible that some staff at the  
school had been exposed to carbon monoxide. She advised that carbon monoxide was  
produced when fuel was burned, and if it did not burn efficiently, there was an “increased risk.”  
The staff’s reported symptoms matched the symptoms for carbon monoxide exposure. The  
most common symptoms included headaches, dizziness, weakness, upset stomach, vomiting,  
chest pain, and confusion.  
3
150, 4600 Jacombs Road, Richmond, B.C. V6V 3B1  
Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
[19]  
[20]  
On December 7, 2017, an HVAC contractor inspected the newly installed units and found one  
mechanical failure on the rooftop unit that supplied the school’s multi-purpose room. The claim  
file documents indicate that the necessary repairs were made to that HVAC unit soon after the  
issue was identified.  
In an email to the school’s staff dated December 11, 2017, the principal noted that she had  
received some air quality concerns in different areas of the school. The issue with the HVAC  
system attached to the multi-purpose room had been resolved and the science wing had been  
“checked” as well. Since then, another concern was raised in relation to the leadership room.  
The HVAC contractors were going to attend the school later on that day to review the entire  
ventilation system.  
[21]  
[22]  
In an email to several school administrators dated December 14, 2017, the worker noted that  
the HVAC contractors opened the vents in her classroom to allow for more outside air to come  
in. This was helpful when the equipment was not being used. However, she was still getting  
headaches when the foundry was running for casting purposes and during welding. This issue  
needed to be addressed as soon as possible given that it was a school-wide issue and not just  
related to her classroom.  
On Friday, December 15, 2017, the worker attended an emergency room department and  
reported intermittent headaches and nausea. She last felt these symptoms while working at the  
school one day earlier, but they had settled by the time she reported to the hospital. She was  
concerned about possible carbon monoxide exposure while working in her metal classroom.  
She experienced symptoms when the acetylene torches and metal foundry were operating at  
the same time. The worker’s vital signs were taken and she underwent bloodwork. Her  
carboxyhemoglobin level was documented at 2.8. The attending physician noted there was no  
evidence of carbon monoxide poisoning. The worker was advised to return to the hospital if she  
had any significant symptoms so that her carboxyhemoglobin levels could be reassessed while  
she was symptomatic. The worker was discharged from the hospital with a final diagnosis of  
“headache”.  
[23]  
[24]  
On December 18, 2017, a Board occupational hygiene officer (OHO) attended the school to  
investigate/test the air quality in various areas of the school including the metal shop. By that  
time, the employer had shut down some of the welding operations in the shop. The foundry was  
still operating, but no welding or cutting tasks were being undertaken. Testing revealed no  
carbon monoxide in the air of the work locations, and carbon dioxide levels were reportedly  
within acceptable levels.  
The OHO noted that the employer’s response to the indoor air quality complaints had failed to  
sample for contaminants possibly related to those complaints. This contravened the Board’s  
Occupational Health and Safety Regulation (OHS Regulation). As such, the OHO issued an  
order of compliance to ensure the employer updated its procedures on responding to indoor air  
quality complaints to include such sampling (order #1). Additionally, the OHO found that the  
employer’s welding, cutting, and similar processes were not being carried out using adequate  
4
150, 4600 Jacombs Road, Richmond, B.C. V6V 3B1  
Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
ventilation pursuant to the requirements of the Canada Standards Association. As such, an  
order of compliance was issued to ensure these requirements were being followed (order #2).  
[25]  
[26]  
In a follow-up report dated January 29, 2018, the OHO noted the employer was in compliance  
with order #1 as it had updated its procedures for responding to indoor air quality complaints to  
include sampling for contaminants. The employer was also in compliance with order #2, as it  
had ordered local exhaust ventilation to be installed. In the meantime, it had ceased plasma  
welding and oxy/acetylene cutting until the installation was done.  
From February 19 to 21, 2018, the employer conducted air quality testing in the metal shop. A  
Q-track monitor was placed in the welding bay at table height (3 feet off the ground and 1 foot  
away from the exhaust hood). The monitor measured the carbon monoxide and carbon dioxide  
levels, and logged data for 3 consecutive days at 120 second intervals. At that time, students  
were using the welding equipment but not the casting or grinders. They were also not permitted  
to use the oxy-torch or handheld plasma cutters. The vents in the grinder and welding booth  
were running when classes were in session.  
[27]  
The Q-track monitor collected data for a total of 1,440 samples. The carbon monoxide levels  
were recorded mostly at 0 parts per million (ppm)3 with a range between 0.1 and 2.9 ppm on the  
rare occasion. The maximum level recording was documented at 7.6 ppm (on one occasion),  
but it went down to 0 ppm in the next sample (2 minutes later). The 8-hour time weighted  
average (TWA)4 concentration was 0.1 ppm. The Board’s permissible TWA exposure limit for  
carbon monoxide is 25 ppm. The carbon dioxide levels were mostly recorded below 1,000 ppm  
with the exception of a maximum level recording of 1,616 on one occasion. This went down to  
970 ppm in the next sample (2 minutes later). The TWA level was recorded at 880 ppm. The  
Board’s permissible TWA exposure limit for carbon dioxide is 5,000 ppm.  
[28]  
The employer commissioned an engineering firm to assess the adequacy of the ventilation  
system that serviced the metal shop (at the 2 welding booths and forging/foundry area) to  
ensure compliance with the current industry standards/codes. In the corresponding March 19,  
2018 report, the consultant noted that the existing areas utilized overhead capture hoods with  
3 localized exhaust fans installed on the roof. In the forge/foundry area, the overhead hood was  
an older system, which did not provide adequate exhaust of the heat and fumes generated by  
the casting process. While the airflow from the exhaust fan was sufficient (at 4000 cfm5), the  
design of the canopy hood and positioning of the forge made the overall system inadequate.  
Additionally, the 2 welding booth areas were serviced with 2 individual 1,700 cfm exhaust fans,  
which were connected to canopy exhaust hoods. The consultant noted that the existing  
overhead canopy hood capture system was “not the best system” for welding and cutting. The  
recommended exhaust air velocities for welding was 2,000 to 2,500 fpm6, and the existing air  
3
1 ppm = 1 part of gas per million parts of air by volume  
TWA limits refer to exposure over a nominal 8-hour work period.  
cubic feet per minute  
feet per minute  
4
5
6
5
150, 4600 Jacombs Road, Richmond, B.C. V6V 3B1  
Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
velocity was at 1,800 fpm. The consultant provided some recommendations for upgrades to the  
existing design of the canopy hoods and ventilation systems in the 2 areas.  
[29]  
Based on the engineering report, the employer continued to restrict the use of some welding  
equipment in the metal shop.  
[30]  
[31]  
Sometime in March 2018, portable welding fume extractors were placed in the metal shop.  
On May 24, 2018, the worker filed a teleclaim application for compensation with the Board  
(teleclaim application). She reported that on or about November 3, 2017, she started developing  
headaches, fatigue, nausea, and dizziness. Her symptoms got worse throughout November  
2017. She had notified the employer’s health and safety committee (which she was a member  
of). She attended a local hospital in December 2017 and was diagnosed with carbon monoxide  
exposure. Her carbon monoxide level was at 2.8, but she had not been using the shop  
equipment for about 36 hours prior to testing. The worker advised that she did not miss any time  
from work as a result of the indoor air quality issues at work.  
[32]  
[33]  
The employer’s report of injury dated May 29, 2018 documented the same information as the  
worker’s teleclaim application. The employer confirmed that the worker did not miss any time  
from work.  
On May 30, 2018, the worker sought medical attention from her family physician, Dr. Hollman.  
The worker reported that in mid-October 2017, she started developing headaches and nausea  
while working in the metal shop. Her symptoms were worse at work. The carbon dioxide levels  
at her school had been “very high” and she could not work. Dr. Hollman submitted a report to  
the Board stating that the worker was unable to work at that time. She diagnosed the worker  
with “possible recurrent carbon monoxide [and] carbon dioxide poisoning.”7  
[34]  
[35]  
The worker stopped working thereafter.  
On June 4, 2018, the worker attended a health and safety meeting to discuss the air quality  
issues in the school. The Board’s OHO was present at that meeting. The worker advised that  
she had been trying to get pregnant since February 2018 and was concerned about being  
exposed to toxins in the metal shop. Discussions about accommodating the worker ensued  
thereafter. The OHO noted that there were specific rules regarding reproductive toxins in the  
workplace. The allowable exposure limits were different for workers who were trying to get  
pregnant.  
[36]  
On June 11 and 13, 2018, the employer conducted further carbon monoxide testing using a  
Gas Alert Max Monitor. A substitute teacher wore the monitor while metal shop classes were in  
session. The teacher confirmed that typical class activities took place each day including  
welding, foundry work, and plasma cutting. The data indicated a spike in the carbon monoxide  
7
All quotes are reproduced as written, except as noted; block capitalization removed.  
6
150, 4600 Jacombs Road, Richmond, B.C. V6V 3B1  
Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
levels at the start and end of testing. Other than that, no airborne carbon monoxide was  
detected on the first day. On the second day, carbon monoxide was detected at 5 ppm  
between 12:30 p.m. and 12:45 p.m. The employer’s OHS manager later advised the Board  
that the carbon monoxide monitor was calibrated before use on the first day and at the end of  
testing on the second day. For some reason, the data included the calibration in the results  
(which explained the momentary spike at the beginning and end of testing). The carbon dioxide  
levels were not tested because the Board’s OHO had requested that take place only after the  
new fume extractor had been installed.  
[37]  
In June 2018, the worker told a Board officer that her symptoms of fatigue, nausea, headaches,  
and dizziness started in mid-October 2017, and not in November 2017 as indicated on her  
teleclaim application form. Her symptoms were “not bad” on Mondays or Tuesdays. They got  
progressively worse from Wednesday to Friday. She believed that the build-up of carbon  
monoxide/dioxide made her feel worse at the end of the week. She felt better on the weekends.  
She missed sporadic time from work beginning in January 2018. She stopped working around  
May 29, 2018 as her doctor said that she was not getting better and needed to be off work.  
Additionally, she had 2 miscarriages since she started working at the school and her doctor said  
that she did not need the added stress. She was going to be off work for the remainder of the  
school year.  
[38]  
On July 30, 2018, Dr. Hollman noted that the worker was trying to get pregnant. The worker  
reported that she and her partner had stopped using condoms in February 2018. She had heavy  
and painful menstrual cycles. Dr. Hollman diagnosed “[a]bnormal uterine bleeding and  
difficulties getting pregnant.” She ordered blood work, which revealed normal blood count, iron  
studies, and thyroid stimulating hormone levels.  
[39]  
[40]  
An August 2018 pelvic ultrasound revealed the worker had a large hypervascular uterine mass,  
which was most likely a fibroid, with normal endometrium. A subsequent MRI revealed that the  
uterine fibroid measured up to 77 mm in diameter. The endometrium and ovaries were normal.  
On August 22, 2018, the worker consulted with Dr. Wroz (a gynecologist) and advised that she  
had been trying to get pregnant for the past 6 months. She was concerned that her fibroid and  
infertility were related to her work exposure to carbon monoxide/dioxide. Dr. Wroz assured her  
that there was no evidence to support her theory. He counselled the worker on infertility and  
noted that up to 80% of couples do not conceive within the first year of trying.  
[41]  
On August 27, 2018, Dr. Hollman noted the worker had ongoing painful menstrual cycles. The  
worker requested Dr. Hollman to fill out a form for modified duties (which she did). The worker  
was cleared to return to modified duties in September 2018. Dr. Hollman diagnosed “difficulties  
getting pregnant, menorrhagia with dysmenorrhea with large uterine fibroid, previous poisoning  
from carbon monoxide and carbon dioxide at work.”  
7
150, 4600 Jacombs Road, Richmond, B.C. V6V 3B1  
Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
[42]  
[43]  
In August 2018, the employer offered the worker a reassignment position given that she was  
trying to get pregnant. The worker was not happy with the initial reassignment and declined the  
offer.  
On September 10, 2018, the worker told Dr. Hollman that her school was deemed unsafe due to  
carbon monoxide, carbon dioxide, and other toxic fumes. The employer was not doing what it  
needed to do, and was not providing her with alternate work duties. Dr. Hollman provided a  
medical note stating that the worker needed to stay off work for the remainder of the school  
year.  
[44]  
On September 20, 2018, the worker told a Board officer that she was looking for a new  
gynecologist because Dr. Wroz advised that her work environment did not cause her  
miscarriages. She disagreed with Dr. Wroz because carbon monoxide was a well-known  
reproductive toxin. Due to her exposure at work, she had suffered 3 miscarriages.  
[45]  
[46]  
On October 1, 2018, the worker told Dr. Wroz that she had some information from the Board  
showing that her work environment was inadequately ventilated and the presence of  
reproductive toxins. Dr. Wroz referred the worker to a fertility specialist, Dr. Bediway.  
On October 11, 2018, the worker told a Board officer that the employer should test the air  
quality in the metal shop with all the equipment running simultaneously. In her typical work day,  
all the equipment was running for 3 to 4 hours per day. The employer was not doing this type of  
testing because it knew that it was unsafe to do so, and it did not want to expose anyone else to  
the risks. It was a “no-brainer” that there was something wrong in the work environment  
considering the employer would not even perform this type of testing. The worker felt that the  
employer was “sandbagging” the investigation because new ventilation was going to be installed  
in the following week. Once this happened, it would be impossible to obtain the relevant data.  
The Board officer asked the worker if she had any confirmed past pregnancies, or whether she  
sought medical treatment for her pregnancies/miscarriages. He noted the medical reports from  
Drs. Wroz and Hollman specifically documented the worker’s inability to conceive, but did not  
mention conception or miscarriage. The worker advised that she did not seek medical attention  
for her miscarriages.  
[47]  
[48]  
Between mid-October 2018 and January 2019, the worker sought treatment by a naturopathic  
doctor, Dr. Spooner. The worker underwent a urine element analysis that tested for potential  
toxic elements including aluminum, antimony, arsenic, bismuth, cadmium, cesium, gadolinium,  
indium, lead, mercury, nickel, tellurium, thallium, thorium, tin, tungsten, and uranium. In his  
corresponding report, Dr. Spooner provided some general information on each element. He also  
documented the worker’s urine test results, but did not address whether there was evidence of  
any occupational exposure.  
Sometime in October/November 2018, the employer carried out the recommended  
modifications to the hood design over the foundry in the metal shop.  
8
150, 4600 Jacombs Road, Richmond, B.C. V6V 3B1  
Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
[49]  
On November 16, 2018, the worker saw Dr. Bediway in relation to her fertility issues. He noted  
the worker had been trying to get pregnant for the past 8 months (starting in February 2018).  
The worker’s past medical/gynecological history was documented in detail without mention of  
any prior miscarriages. Dr. Bediway recommended further hormone testing to assess the  
worker’s ovarian reserve. He noted that cavity-uterus fibroids increased the likelihood of  
miscarriages, and recommended the worker undergo surgical removal of her fibroid.  
Dr. Bediway also addressed the worker’s concerns about being exposed to biochemical hazards  
in her work environment and how it related to her inability to conceive for the past 8 months. He  
told the worker that there was limited information on whether the biochemical hazards that she  
was exposed to impacted her ovarian reserve.  
[50]  
On November 21, 2018, the employer conducted further air quality testing in the metal shop  
while classes were in session. The teacher advised that in the first two blocks, the kiln and  
welding machines were running for the majority of the time. In the third block, the students  
mainly used the hand tools and some minor welding took place. In the last block, the lathe,  
welding, and kiln were running for 90% of the time. The data revealed no detection of airborne  
carbon monoxide. For the most part, carbon dioxide levels were below 1,000 ppm, with the  
exception of a few sporadic readings over 1,000 ppm, with a maximum level of 1,774 ppm  
during a single 2-minute interval, which went down to 983 ppm immediately thereafter.  
[51]  
On December 5, 2018, the worker told a Board officer that Dr. Bediway told her that the medical  
system did not allow him to comment on a connection between her fibroid and heavy metal  
exposure. He was not allowed to comment on why her hormones were “out of whack” and the  
medical system did not allow him to look into why they were “out of whack.” He could only treat  
symptoms. The worker also advised that Dr. Spooner said that her “problems” were related to  
exposure to heavy metals in her job. He said that her exposure to carbon monoxide was the  
“least of her worries.” Dr. Spooner’s testing revealed that her levels were high for quite a few  
heavy metals that were reproductive toxins such as lead, mercury, and cadmium. The worker  
noted that lead and cadmium were known reproductive toxins. Lead reacts with cadmium and  
they “feed off each other” resulting in the cadmium becoming more toxic than it would be on its  
own. Dr. Spooner advised that it was the lead and cadmium in her system that was blocking her  
hormones. This caused the formation of her fibroid and inability to conceive. Dr. Spooner  
treated the worker with a series of injections in order to extract the heavy metals from her  
system.  
[52]  
[53]  
On December 7, 2018, Dr. Wroz noted the worker gave him some studies pertaining to heavy  
metal exposure and fibroids. He referred the worker to a fertility clinic to see Dr. Yupze, an  
endocrinology/infertility specialist with an expertise in heavy metal exposure and infertility.  
In a claim investigation report dated January 8, 2019, two Board OHOs addressed the worker’s  
potential exposure to carbon monoxide/dioxide and other substances in her welding  
environment in the school. The OHOs noted that they had reviewed the claim file documents  
including the chronology of events and timelines in relation to the worker’s reported symptoms,  
the air sampling testing/data, the March 2018 engineering report, and various literature on  
9
150, 4600 Jacombs Road, Richmond, B.C. V6V 3B1  
Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
carbon monoxide and other contaminants. The OHOs also spoke with the initial OHO who had  
conducted the air sampling at the workplace in December 2017; they also reviewed his  
corresponding inspection reports and compliance orders.  
[54]  
The OHOs noted that carbon monoxide is an odorless and colorless gas that provides no  
warning until exposure results in adverse health symptoms. Symptoms of mild carbon monoxide  
poisoning include headaches, dizziness, nausea, and vomiting. It was known that welding tasks  
do not normally generate carbon monoxide at harmful levels of any concern except in cases of  
confined work spaces where it can accumulate over time. In BC, the OHS Regulation  
established exposure limits for contaminants with references to the American Conference of  
Governmental Industrial Hygienists (ACGIH) exposure limits. The relevant exposure limits were:  
Carbon monoxide:  
TWA-8 hour  
STEL-15 minute8  
25 ppm  
100 ppm  
Carbon dioxide:  
TWA-8 hour  
STEL-15 minute  
5,000 ppm  
15,000 ppm  
[55]  
[56]  
The OHOs noted that carbon dioxide levels can be used as an indicator of sufficient outdoor air  
being delivered to the work environment. Normally, indoor levels around 1,000 ppm are a good  
indication that the HVAC system is functioning well for the work environment.  
Regarding the worker’s exposure to carbon monoxide and carbon dioxide, the OHOs noted the  
following:  
The new HVAC systems were installed in early October 2017, at which time the contractor  
noticed that the fume extraction system servicing the metal shop was not working properly  
(loose belt and electrical breaker locked out). The necessary repair was completed without  
delay. Although it was not known how long this unit was not working properly, it was  
possibly since the start of the school year in September 2017. While welding operations  
typically do not generate high levels of carbon monoxide, it was possible during this time  
period that carbon monoxide from welding and forging operations was permitted to  
accumulate at low levels in the metal shop. It was unlikely that airborne carbon monoxide  
ever approached the exposure limit because there were 2 other exhaust fans servicing the  
shop. Additionally, the work activities were student based, and not production based.  
On December 7, 2017, the HVAC contractor inspected all components of the new  
HVAC systems and found a mechanical failure on the rooftop HVAC unit servicing the  
multi-purpose room. The necessary repairs were made to this unit soon after being  
identified. Improper operation of heating components of an HVAC system can give rise to  
8
STEL limits refer to short-term or peak exposures  
10  
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Tel: (604) 664-7800 | 1-800-663-2782  
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WCAT Decision Number:  
A2100606 (August 17, 2022)  
incomplete combustion of natural gas, which can give rise to elevated carbon monoxide  
levels in a workplace. Although there was no evidence that the mechanical failure of the  
rooftop HVAC system failed in a way that would give rise to carbon monoxide emission, this  
was possible, and aligned with the staff’s air quality complaints.  
A further HVAC issue within the metal shop was identified when the engineering firm  
assessed the exhaust ventilation system. The report indicated that while the exhaust fans  
were, for the most part, properly sized for the scope and nature of welding and forging work,  
the canopy hood design was outdated. As such, recommendations to upgrade the  
ventilation design were provided (to include a source capture type design). This poor  
ventilation design would likely have contributed more to the accumulation of welding fumes  
in the work area rather than welding gases, as gases are light and will become easily  
entrained in the upward ventilation flow.  
The Board’s air quality inspection on December 18, 2017 did not find any evidence of  
elevated levels of carbon monoxide or carbon dioxide. Repeat measurements were  
undertaken by the employer in February 2018 and again in June 2018, which found  
comparable levels, all well below the respective exposure limits. All the HVAC system  
defaults had been repaired by the time that these surveys took place.  
[57]  
Overall, the OHOs noted that the timeline of the air quality complaints from the employer’s staff  
aligned with the HVAC malfunctions. Therefore, it seemed likely that the HVAC malfunctions  
may have caused, or at least contributed to, the air quality complaints from October 2017 to  
early December 2017. However, after December 2017, staff in the multi-purpose room and  
science room did not continue to report adverse health symptoms or air quality complaints.  
However, the worker reported ongoing symptoms, which she attributed to the air quality in the  
metal shop. In that regard, while the exhaust ventilation system in the metal shop was  
determined to be less than optimal, ventilation gases are light and would have easily become  
entrenched in the ventilation flow created by the 3 exhaust fans. It was unlikely that carbon  
monoxide or carbon dioxide levels would have approached or exceeded the respective  
exposure limits during typical student tasks. For these reasons, it was expected that the  
airborne levels of welding gases in the metal shop would have been very low despite the poor  
ventilation design.  
[58]  
The OHOs also considered the worker’s potential exposure to welding/casting fumes. They  
noted that welding tasks and plasma cutting can generate welding fumes such as iron oxide,  
magnesium oxide, and manganese oxide. Aluminum forging can generate airborne aluminum  
oxide. The OHOs outlined the exposure limits for these contaminant as set out in the OHS  
Regulation, which I have not summarized. Regarding the worker’s potential exposure to welding  
fumes, the OHOs noted the following:  
Given the fan failure identified in October 2017, it was possible that welding fumes may  
have accumulated in the shop at low levels in the one-month time period (from the start of  
the school year in September 2017 to early October 2017). Any gases would not likely have  
lingered in the shop as they would have been drawn up in the air flow created by the other  
11  
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Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
2 exhaust fans and the general HVAC system servicing the metal shop. Additionally,  
students routinely entered and exited the metal shop and this movement would have also  
provided some air movement and helped to facilitate any accumulation of fumes out of the  
shop, where it would have been drawn into the school HVAC air systems servicing the  
common areas and adjacent work locations.  
While the worker believed that the sampling was not indicative of the full spectrum of tasks  
undertaken in the metal shop, there were exhaust fans and a general HVAC system in the  
shop. The low levels of carbon monoxide and carbon dioxide levels measured from the air  
quality testing indicated that these ventilation systems were serving to remove contaminants  
from the work environment.  
While there was no available data confirming airborne levels of metal fume present in the  
metal shop during typical student tasks, there were 2 large canopy hood exhaust ventilation  
systems servicing both the forge and welding areas. The fans servicing these areas were  
assessed by a ventilation engineer, and while the canopy hood design was determined to be  
of a poor design for the scope of work, the exhaust fans were more or less appropriately  
sized for the scope and nature of the student-centered tasks. Nonetheless, the employer  
took steps to restrict the use of certain equipment within the shop and/or put conditions on  
their use until such time that the recommended upgrades could be completed. As such, it  
was unlikely that welding fume and gas levels would have approached or exceeded the  
BC regulated exposure limits for these substances.  
The findings of the investigation suggested that it was unlikely that the worker was exposed  
to harmful levels of metal oxide fumes during her work in the metal shop.  
[59]  
On January 17, 2019, Dr. Hollman noted the worker’s PAP test revealed atypical squamous  
cells. The worker believed this was caused by her exposure to heavy metals at work. However,  
Dr. Hollman advised that these abnormalities were usually caused by human papillomavirus  
(HPV) disease.  
[60]  
[61]  
On January 28, 2019, Dr. Bediway noted that the worker’s ovarian screen//hormone testing  
came back normal, which supported that she had a normal ovarian reserve.  
On March 5, 2019, the worker was seen by another gynecologist, Dr. Adams, in relation to her  
abnormal PAP smear. He noted the worker had questions about heavy metal exposure and  
cervical dysphasia. Dr. Adams advised that the pathophysiology of dysplasia was well  
understood, and in the vast majority of cases, it was HPV-related. To the best of his knowledge,  
there was no known causal association with heavy metal exposure.  
[62]  
[63]  
On March 21, 2019, the worker underwent an x-ray that revealed a normal-appearing  
endometrial cavity. Other than the fibroid, no other abnormality was seen.  
On March 29, 2019, the worker saw Dr. Yupze, and advised that she had been trying to get  
pregnant for the past year. Her partner had a son from a previous relationship, but she had  
12  
150, 4600 Jacombs Road, Richmond, B.C. V6V 3B1  
Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
never been pregnant. The worker reported that her work environment had very poor ventilation.  
She believed that she had been exposed to various substances that could be reproductive  
toxins such as cadmium, mercury, and carbon monoxide.  
[64]  
[65]  
Dr. Yupze noted the worker had brought a huge 3-ring binder full of articles, test results,  
statistics, and other materials addressing environmental toxins and their effects on fertility. She  
also provided articles suggesting a relationship between these substances (and cadmium in  
particular) and uterine fibroids. Dr. Yupze noted these substances were considered to be  
endocrine disruptors, and the worker suggested that they caused her uterine fibroid. Dr. Yupze  
advised that he was not aware of such correlation. To his knowledge, the presence of fibroid  
ceilings had to be present in order for a fibroid to develop.  
The worker went on to tell Dr. Yupze that physicians do not look at hormone levels “below the  
line” but only looked at levels that were “above the line.” Dr. Yupze was not certain what the  
worker was referring to in that regard. He noted that she had previously undergone 2 endocrine  
studies, which showed normal hormone levels. Her thyroid level was normal and she had a  
good ovarian reserve. Dr. Yupze had no explanation for why the worker had not yet become  
pregnant; however, it was not uncommon that women of her age did not get pregnant within  
12 months of trying. Unexplained infertility, which was the worker’s diagnosis at that point,  
accounted for at least 50% of his patients being assessed for fertility issues. That said, there  
was an association between the worker’s failure to conceive and her fibroid. Dr. Yupze  
recommended the worker undergo surgical removal of her fibroid, and try to conceive on her  
own for approximately 6 months thereafter.  
[66]  
[67]  
Dr. Yupze noted the worker was likely not completely satisfied with their discussion. He was not  
trying to convince her that all her theories on chemical endocrine disrupters were irrelevant to  
her case. However, based on the endocrine testing done up to that point in time, there was no  
evidence of anything actually having been affected.  
In an investigation report dated March 29, 2019, a Board OHO further considered the worker’s  
potential exposure to heavy metals (including cadmium) during her work as a welding instructor.  
In doing so, the OHO reviewed the material safety data sheets for products used in the metal  
shop, the employer’s exposure control plan (ECP) and risk assessment, the prior OHO  
inspection reports and associated documents, and relevant literature. The OHO noted the  
following:  
Welding will produce fumes containing various metals. The specific form and concentration  
of metals present in welding fume and dust will depend on the composition of the filler metal,  
base metals, metal coatings, atmosphere, flux, and the welding process. Welding fumes are  
essentially a mixture of complex but often predictable metallic oxides, fluorides, and  
silicates. Welding processes may involve the metals themselves and the use of a filler or  
flux. Welding may occur on new clean stock metal, new metal with residual compounds from  
manufacture, and/or used metal with residual contamination from prior use, including  
coatings.  
13  
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Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
The employer’s ECP for welding fumes listed the products used in the metal shop. From the  
employer’s inventory of products, none of the products used contained cadmium. Some  
metal products, such as steel, could be plated with a thin layer of cadmium to increase  
resistance to corrosion. This cadmium coating was normally between 5 and 25 micrometers  
in thickness. It was unknown if the school had any plated materials; however, given the  
extremely thin coating and low level of use, it was unlikely that this created a hazardous  
exposure.  
Other metals found in the products used in the metal shop included manganese, iron,  
copper, and aluminum. The products also contained titanium dioxide, sodium fluoride,  
kaolin, calcium fluoride, barium compounds and mica-like minerals.  
Based on the engineering report of March 2018, the capture hood in the forge area did not  
provide adequate exhaust of heat and fumes generated by the casting process, and the  
welding area had an air velocity below what it should be. However, the size of the metal  
shop would provide some general dilution of contaminants. Even though the exhaust fans  
were not performing optimally, they had some capacity to remove gases and fumes.  
Welding fume was generated daily while students worked on projects. However, the small  
number of students using the equipment at any one time kept the level of contaminants low.  
When students received instruction and caught up on paperwork, there were no  
contaminants generated. In the instructional setting at school, the level of welding fume  
contaminants generated were lower than in a production facility. Therefore, it was likely that  
the worker experienced frequent exposure to low levels of welding fume contaminants  
through her work as an instructor.  
[68]  
On April 25, 2019, Board medical advisor Dr. Raghukumar provided a lengthy opinion  
addressing the worker’s potential exposure to carbon monoxide and the cause of her uterine  
fibroid. She summarized the worker’s exposure history, key reporting documents, the Board’s  
investigation reports, and medical record, which is in keeping with my summary above.  
Dr. Raghukumar noted the worker attended the hospital in mid-December 2017. Examination of  
her vital signs were noted to be stable in relation to her temperature, pulse, respiratory rate,  
blood pressure, and oxygen saturation levels. The remainder of the examination findings were  
unremarkable. The worker’s blood work results were unremarkable in relation to her white blood  
cell count, hemoglobin, electrolytes, renal function, and blood gases. Her carboxyhemoglobin  
was reported at 2.8, which was normal. In Dr. Raghukumar’s opinion, there was no confirmed  
diagnosis of carbon monoxide poisoning.  
[69]  
Dr. Raghukumar also opined that the worker’s fibroid was unrelated to her work. She noted that  
uterine fibroids were mostly benign gynecologic tumors in women of reproductive age. They  
were common with about 77% of women likely to develop them in their lifetime. The medical  
literature documented various known risk factors for uterine fibroids including a patient’s age at  
menarche, parity, ethnicity, and weight/obesity. Dr. Raghukumar was unable to find any specific  
epidemiological studies pertaining to uterine fibroids among welders. She noted that fibroids  
were not listed among the known health hazards to welding fume exposure (as per the  
14  
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Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
information on health impacts of welding from the Canadian Centre for Occupational Health  
Safety and Government of Canada).  
[70]  
On June 28, 2019, the Board requested Dr. Spooner to provide further information regarding the  
worker’s diagnosis, causation, and treatment in relation to her reproduction/fertility/fibroid  
issues. Dr. Spooner forwarded his chart notes to the Board (which were previously submitted)  
but did not provide any new information or opinion on the other requested matters.  
[71]  
[72]  
In a clinical record dated July 17, 2019, Dr. Wroz noted that the worker was approximately  
10 weeks pregnant.  
The worker submitted an information sheet on acceptable indoor air quality levels to the Board.  
It notes that the Board publishes occupational exposure limits for various air quality  
contaminants including carbon dioxide, carbon monoxide, and dust. Additionally, standards for  
acceptable indoor air quality have been developed by ASHRAE9 to establish minimum  
requirements for optimal health and comfort in buildings, and in particular, office environments.  
According to ASHRAE, carbon dioxide levels below 1,000 ppm (TWA) indicate that there is  
adequate air circulation for indoor environments. For carbon monoxide, levels of indoor  
environments should generally not exceed 5 ppm (TWA).  
[73]  
The worker submitted various other documents including: safety data sheet information on  
acetylene and Blueshield 8; school emails addressing OHS issues and, in particular, a  
December 2019 incident whereby a carbon dioxide detector was beeping in the metal shop as a  
result of the acetylene torch being left open slightly; hand-written notes from OHS committee  
meetings held at the school; minutes from a joint health and safety district committee meeting  
that documented the December 2019 carbon dioxide incident; pages from the employer’s ECP;  
various articles addressing the effects of exposure to various types of airborne substances, the  
relationship between heavy metals accumulated in the body and the development of uterine  
fibroids and infertility, and general exposure to hazardous fumes and particles in the welding  
field; an August 2017 quote for exhaust fume downdraft tables for various high schools within  
the employer’s district; and information about her reassignment. As mentioned earlier, I have  
reviewed all this information in my adjudication of the appeal, but will not summarize it.  
WCAT Oral Hearing  
[74]  
The worker’s oral hearing testimony repeated much of the information that was already in the  
claim file. As such, the following is only a brief summary of her testimony dealing with any new  
or contradictory information:  
In the first 2 weeks of school in September 2017, she conducted safety tests in the metal  
shop and the welding equipment was not used.  
9
The American Society of Heating, Refrigerating, and Air-Conditioning Engineers  
15  
150, 4600 Jacombs Road, Richmond, B.C. V6V 3B1  
Tel: (604) 664-7800 | 1-800-663-2782  
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WCAT Decision Number:  
A2100606 (August 17, 2022)  
Her job was not stationary. She was always “on the go” while helping students at various  
stations including the welding booth, foundry, and milling machines. All the equipment was  
in operation at the same time. She stood behind students and watched them weld.  
She did not notice much difference in her symptoms after the employer had shut down some  
of the welding processes in December 2017; however, it helped to open the big bay door.  
She used to stand next to the foundry to take out the impurities. This is where the engineer  
found that the ventilation was inadequate.  
Regarding the employer’s June 2018 air quality sampling, the substitute teacher who wore  
the monitor was working on his own projects and letting the students do “whatever.” He  
showed the worker what he worked on during class.  
Between September 2017 and May 30, 2018, she sporadically missed 4 or 5 days from  
work because she felt unwell. Most of her medical appointments were scheduled after  
school hours.  
In September 2019, two students passed out around the welding booths. Other students  
had passed out in 2018. She did not know if this was a coincidence, but it was relevant.  
She showed Dr. Raghukumar’s opinion to her treating physicians including Dr. Bediway. He  
knew that she had a compensation claim but did not want to get involved. She showed the  
opinion to Dr. Spooner as well, and he said that it was a typical Board response.  
She had been trying to get pregnant since 2016. She had 2 miscarriages between January  
and April/May 2018. She had no prior miscarriages.  
She became pregnant in 2019, but there were a lot of complications. Her baby had a stroke  
while still “inside.” The hospital wanted to terminate the pregnancy when she was 5 months  
pregnant. Her son was born on January 20, 2020. She got pregnant naturally.  
Submissions  
[75]  
[76]  
The worker argued that the Board OHO had determined that the ventilation in the metal shop  
was not up to code and inadequate, and the March 2018 engineering report supported that  
fumes were not being removed from the classroom. This supported her position that she was  
inhaling toxic fumes.  
The worker also argued that the employer’s air quality testing did not accurately reflect what she  
was exposed to because some of the equipment in the metal shop had been shut down in  
December 2017. The February 2018 test results were inaccurate because the Q-track  
monitoring equipment was placed 5 feet away from the aluminum foundry. The worker argued  
that the welding particles/fumes were still in the air, even if not condensed in the welding booth  
area that was tested. She did not stand in front of the welding machine for the entire class.  
Irrespective of that, the recorded carbon dioxide levels went above 1,000 ppm, which exceeded  
16  
150, 4600 Jacombs Road, Richmond, B.C. V6V 3B1  
Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
the exposure limits. This supported her position that she was exposed to toxic levels of airborne  
substances.  
[77]  
[78]  
The worker submitted that the medical journals established a link between heavy metals and  
fibroid growth. The employer acknowledged that the metal shop had reproductive toxins, and  
that she was exposed to them. This was the reason that she was reassigned to a different  
position. These reproductive toxins caused her uterine fibroid and subsequent miscarriages.  
The employer argued that the medical evidence did not establish that the worker had carbon  
monoxide poisoning, or that she was exposed to toxic levels of carbon monoxide. The employer  
relied on the various air quality testing performed by the Board and employer, as well as the  
Board’s OHO’s investigation reports as support for its position in that regard. The employer also  
argued that the medical evidence did not establish an occupational link between the worker’s  
uterine fibroid and exposure to heavy metals/toxic substances during her employment. It also  
did not support that the worker had suffered miscarriages as a result of any occupational  
exposure. The employer noted that the worker had been assessed by several specialists, none  
of whom supported her position on this matter.  
Applicable Law and Policy  
[79]  
WCAT must make its decision on the merits and justice of the case, but in so doing, must apply  
policy of the Board’s board of directors that is applicable in the case. The Board’s Rehabilitation  
Services and Claims Manual, Volume II (RSCM II)10 contains the policy applicable to this  
appeal.  
[80]  
[81]  
Section 136(1) of the Act states that compensation is payable for an occupational disease that  
is due to the nature of a worker’s employment.  
The Act defines an occupational disease as any disease: (1) mentioned in Schedule 1 to the  
Act11; (2) that the Board has designated or recognized as an occupational disease; or (3) that  
the Board has recognized by order in a specific case. The definition includes disablement  
resulting from exposure to contamination.  
[82]  
Policy item C4-25.00 of the RSCM II sets out the following 3 basic requirements for  
compensation under section 136 of the Act: (1) the worker must be suffering from an  
occupational disease; (2) the disease must be, or have been, due to the nature of any  
employment in which the worker was employed; and (3) the worker must be disabled from  
earning full wages where he or she was employed as a result of the disease.  
10  
Several policies in the Board’s RSCM II were amended on February 1, 2020 and April 6, 2020.  
Those amendments apply to this appeal.  
Found in Appendix 2 of the RSCM II. I have referred to “Schedule 1” and “the schedule”  
11  
interchangeably throughout my decision.  
17  
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Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
[83]  
Section 137(2) of the Act addresses occupational diseases that are specifically set out in  
Schedule 1. It states that if a worker contracts a disease set out in the first column of the  
schedule and, at or immediately before the date of the disablement, was employed in a process  
or industry mentioned in the second column of the schedule opposite to that disease, the  
disease is presumed to have been due to the nature of that employment unless the contrary is  
proven. This is known as the rebuttable presumption.  
[84]  
[85]  
[86]  
Policy item C4-25.10 of the RSCM II states that any disease listed in Schedule 1 is by definition  
designated or recognized as an occupational disease. I will address this policy in more detail  
later.  
Item 1(8) of Schedule 1 recognizes carbon monoxide poisoning as an occupational disease that  
is presumed to be due to the nature of employment where there is exposure to products of  
combustion or to any other sources of carbon monoxide.  
Claims for occupational diseases can also be accepted under section 136 of the Act in cases  
where the disease is not listed in Schedule 1, and if the Board has not previously designated or  
recognized a disease an occupational disease. Policy item C4-25.10 states that the lack of a  
prior designation or recognition by the Board of a disease as an occupational disease does not  
mean a claim for such disease will not be considered on its merits. If the merits and justice of an  
individual claim for such a disease warrant its recognition, section 138(3) of the Act provides  
that the Board may by order, designate or recognize a disease as an occupational disease in a  
specific case.  
[87]  
[88]  
[89]  
If a disease is not listed in Schedule 1, but is recognized by regulation or in a specific case, the  
presumption of work causation is not applicable, and it is necessary to establish that the disease  
was due to the nature of the worker’s employment based on the merits and justice of the claim  
(based on a balance of probabilities). The same is true for claims where the requirements of  
section 137 have not been met. In these scenarios, an occupational disease will be due to the  
nature of the worker’s employment if the employment was of causative significance in producing  
the disease. Causative significance means more than a trivial or insignificant aspect.  
Policy item #97.32 governs statements of workers about their own conditions, which I will  
address in more detail later.  
Reasons and Findings  
Did the worker suffer from carbon monoxide poisoning as an occupational disease that was due  
to the nature of her employment?  
Pursuant to the law and policy discussed above, in order for the worker to have a successful  
claim for carbon monoxide poisoning under Schedule 1, the evidence must establish two things:  
(1) that she had carbon monoxide poisoning; and (2) there was exposure to products of  
combustion or other sources of carbon monoxide at work. If both of these conditions are met,  
18  
150, 4600 Jacombs Road, Richmond, B.C. V6V 3B1  
Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
then there is a rebuttable presumption that the carbon monoxide poisoning was due to the  
nature of the worker’s employment. In turn, this will satisfy the first two requirements for  
compensation under section 136 of the Act and policy item C4-25.00.  
[90]  
[91]  
[92]  
Before addressing the merits of the appeal, I note the worker’s claim relates to potential  
exposure that took place throughout the 2017/2018 school year (September 2017 to May 2018).  
Speaking generally, I find the evidence supports that the circumstances from September 2017  
to mid-December 2017 were significantly different than those from mid-December 2017 to  
May 30, 2018.  
More specifically, I find that prior to mid-December 2017, some mechanical issues with the  
newly installed ventilation system and HVAC units had been identified and repaired.  
Additionally, although the employer had received some indoor air quality complaints from its  
staff (including the worker), no indoor air quality testing took place prior to mid-December 2017.  
In addition to this, all the welding equipment in the metal shop was fully operational and running.  
On the other hand, after mid-December 2017, no further mechanical malfunctions with the new  
ventilation system/HVAC units were identified, and the employer did not receive further  
complaints from its staff (other than from the worker) about the indoor air quality. Additionally,  
some of the welding equipment/processes in the metal shop were shut down, and various  
indoor air quality testing took place. I will come back to these points later. For now, it is sufficient  
to say that the different circumstances before and after mid-December 2017 requires  
consideration of the worker’s exposure in each time period separately.  
September 2017 to mid-December 2017  
[93]  
[94]  
The first question to consider is whether the worker suffered from an occupational disease,  
namely carbon monoxide poisoning. Policy item C4-25.10 acknowledges that confirming the  
diagnosis of many occupational diseases may be difficult. This is particularly so for poisoning by  
some of the metals and compounds listed in Schedule 1, the symptoms of which may be similar  
to those caused by common complaints that produce fatigue, nausea, headache, and the like.  
In this case, I agree with the Board that the medical evidence does not establish a definitive  
diagnosis of carbon monoxide poisoning. In deciding this, I note the worker’s bloodwork in  
December 2017 revealed her carboxyhemoglobin level was 2.8. In that regard, I accept  
Dr. Raghukumar’s opinion that the December 2017 hospital test results support that the  
worker’s vital signs and carboxyhemoglobin level were normal, and there was no confirmed  
diagnosis of carbon monoxide poisoning. I consider Dr. Raghukumar’s opinion was based on an  
accurate understanding of the medical record, and therefore place some weight on it in deciding  
this matter.  
[95]  
Contrary to the worker’s assertions to the Board, I find the attending physician at the hospital did  
not diagnose carbon monoxide exposure. In deciding this, I note the worker was discharged  
with a diagnosis of “headache.” I acknowledge the worker’s evidence that her symptoms had  
19  
150, 4600 Jacombs Road, Richmond, B.C. V6V 3B1  
Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
settled by the time she had reported to the hospital. I accept that she had not been using the  
shop equipment for some time prior to testing. However, the fact that she was asymptomatic by  
the time she underwent testing at the hospital does not establish that she was diagnosed with  
carbon monoxide exposure based on her reported earlier symptoms. The hospital records do  
not support the worker’s position on this matter.  
[96]  
I acknowledge that Dr. Hollman’s May 2018 and August 2018 medical reports document  
“possible recurrent” carbon monoxide poisoning and “previous poisoning from carbon  
monoxide.” This may be interpreted to mean the worker was previously diagnosed with carbon  
monoxide poisoning. However, I find that Dr. Hollman’s reports merely repeated the worker’s  
description of her symptoms and the worker’s opinion that her symptoms were related to carbon  
monoxide exposure at work. Dr. Hollman did not document any independent observations of the  
worker’s condition or provide an independent opinion as to the possible causes of the reported  
symptoms. She also did not address the results of the December 2017 bloodwork that revealed  
a normal carboxyhemoglobin level. For these reasons, I place no weight on Dr. Hollman’s  
carbon monoxide diagnosis documented in her medical reports.  
[97]  
While I have found that there is no definitive carbon monoxide poisoning diagnosis, this does  
not necessarily mean that the presumption of causation pursuant to section 137(2) of the Act is  
no longer available to the worker. The absence of a physician’s positive diagnosis of poisoning  
does not determine the issue. This is because the degree of certainty required for a physician to  
make a positive diagnosis may be different from that required under the Act and Board policy to  
reach an adjudicative conclusion that a worker suffers from a disease described in the  
first column of Schedule 1. As mentioned earlier, the standard of proof in compensation appeals  
is the balance of probabilities, subject to section 303(5) of the Act. In McKnight et al. v. Workers’  
Compensation Appeal Tribunal and Board of Education School District No. 5 (Southeast  
Kootenay), 2012 BCSC 1820, the Court determined that it was patently unreasonable to apply a  
diagnostic standard that is higher than this to the question of whether a worker suffers from an  
occupational disease.  
[98]  
[99]  
On this matter, policy item C4-25.10 acknowledges that evidence supporting that an  
occupational disease has been diagnosed is relevant and will generally be given significant  
weight; however, it is not a requirement under section 136(1) of the Act. The question is whether  
it is “at least as likely as not” that the worker has an occupational disease that is designated or  
recognized by the Board. This answer to this question must be based on evidence.  
In this case, there is no direct, physical evidence that the worker suffered from carbon monoxide  
poisoning. The worker’s symptoms were subjective in nature. The evidence of these symptoms  
came from the worker. Policy #97.32 of the RSCM II provides that the statement of a worker  
about his or her own condition is evidence insofar as it relates to matters that would be within  
the worker’s knowledge. Workers’ descriptions of their symptoms are statements about their  
condition and concern matters within their knowledge; however, conclusions about the cause of  
those symptoms drawn from the nature of the symptoms themselves are not within a worker’s  
20  
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WCAT Decision Number:  
A2100606 (August 17, 2022)  
knowledge. With this in mind, I find the nature of the worker’s condition may be inferred from the  
subjective symptoms that she described.  
[100] In that regard, the evidence supports that the worker first reported headaches/migraines and  
nausea to the employer on November 3, 2017. According to the employer’s investigation report,  
she reported headaches, nausea, and exhaustion since late October/early November 2017. She  
reported similar symptoms at the hospital in mid-December 2017. The teleclaim application for  
compensation and telephone records in the claim file also document nausea, headaches,  
fatigue, and dizziness. The teleclaim application recorded the date of injury as November 3,  
2017. On the whole, I find the evidence supports that the worker developed headaches, fatigue,  
nausea, and dizziness sometime in late October/early November 2017. I acknowledge that in  
May 2018 and June 2018, the worker advised that her symptoms started in mid-October 2017.  
However, this information was provided more than 7 months later, and I prefer the worker’s  
evidence that is more contemporaneous to the date of injury.  
[101] I find the worker’s reported symptoms were consistent with poisoning by carbon monoxide. In  
deciding this, I note that in the Board’s January 2019 investigation report, the OHOs advised  
that carbon monoxide is an odorless and colorless gas that provides no warning until exposure  
results in adverse health symptoms. Symptoms of mild carbon monoxide poisoning include  
headaches, dizziness, nausea, and vomiting. This is in keeping with the information  
documented in the employer’s OHS manager’s November 2017 email. The OHS manager  
also stated that the reported symptoms from staff (which I interpret to include those from the  
worker as well) matched the symptoms for carbon monoxide exposure. I consider it reasonable  
to find that as an OHS manager, she had some basic knowledge about symptoms associated  
with carbon monoxide exposure in the workplace. As such, I place some weight on the  
OHS manager’s opinion in deciding this matter. Further, I note that in December 2017, the  
Board OHO attended the school in response to the staff’s indoor air quality complaints and  
measured the carbon monoxide levels. In my view, this supports a finding that the OHO felt the  
reported symptoms were in keeping with potential carbon monoxide exposure.  
[102] In addition to the worker’s reported symptoms, I find that evidence of her being exposed to  
carbon monoxide may be relevant to the diagnosis of her condition. 12 For instance, if there is  
evidence that the worker had symptoms consistent with but not diagnostic of carbon monoxide  
poisoning, evidence that the worker was exposed to carbon monoxide at levels sufficient to  
generate those symptoms would support a diagnosis of carbon monoxide poisoning. Having  
said that, recognition of a condition as an occupational disease by inclusion in Schedule 1 does  
not create a presumption with respect to diagnosis. Section 137(2) of the Act and Schedule 1 do  
not create a presumption that a worker suffers from a particular disease; rather, they create a  
presumption with respect to causation under certain circumstances.  
12  
Paragraphs 102 to 107 of my decision paraphrase part of the discussion of the application of  
Schedule 1 in WCAT-2013-01380.  
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[103] While evidence of the worker being exposed to potentially toxic levels of carbon monoxide  
would support a diagnosis of poisoning, similarly, evidence that the worker was not exposed to  
such toxic levels of carbon monoxide would weigh against the conclusion that she suffered from  
poisoning by carbon monoxide. In these circumstances, it appears that the first question of  
whether the worker suffered from poisoning by carbon monoxide requires consideration of the  
same evidence as the second question of whether the worker was exposed to carbon  
monoxide. As such, the remainder of my analysis relates to the evidence of exposure.  
[104] At this juncture, I note that Schedule 1 does not provide any detail on the specific levels or  
degrees of exposure to carbon monoxide. The exposure limits for various substances are set  
out in the OHS guidelines used by the Board to determine compliance with the OHS Regulation.  
As mentioned earlier, the 8-hour TWA exposure limits for carbon monoxide is 25 ppm, and the  
STEL limit is 100 ppm.  
[105] Policy item C4-25.10 acknowledges that it is not possible to precisely define the amount and  
duration of exposure required in the process or industry described in column 2 of Schedule 1.  
Individual judgment must be exercised in each case to determine their meaning, having regard  
to the medical and other evidence available as to what is a reasonable amount or duration of  
exposure.  
[106] In WCAT-2009-01704, a three-person panel considered exposure to mercury, another  
substance listed in Schedule 1. The panel determined that “exposure” as used in reference to  
mercury in Schedule 1, meant exposure beyond what any person would normally encounter on  
a day-to-day basis living in Canada, and did not mean exposure beyond permissible limits  
established in relation to the OHS Regulation. The panel went on to conclude that exposure to  
mercury beyond what any other person would encounter on a day-to-day basis would be  
sufficient to apply the Schedule 1 presumption of work causation once a worker was found to  
have mercury poisoning, but evidence such as exposure limits in occupational health and safety  
guidelines or scientific literature were still relevant to the question of whether exposure was  
sufficient to cause mercury poisoning.  
[107] Previous WCAT decisions are not binding, but they may provide useful guidance. I accept that  
once it has been determined that the worker suffers from poisoning by a particular substance, it  
is not necessary to demonstrate exposure beyond the limits set in the OHS guidelines in order  
to apply the Schedule 1 presumption. That said, such guidelines may yet be relevant to the  
determination of whether the worker did in fact suffer from poisoning by a specific substance  
such as carbon monoxide.  
[108] In this case, I find there is some evidence that the worker was exposed to carbon monoxide  
around the time of her reported symptoms in late October/early November 2017 to mid-  
December 2017. In deciding this, I note that around the same time frame, other staff members  
at the school also complained about the indoor air quality and reported similar symptoms as the  
worker (headaches, nausea, and exhaustion). The employer’s OHS manager advised that it  
was possible that staff had been exposed to carbon monoxide. In these circumstances, I draw  
22  
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WCAT Decision Number:  
A2100606 (August 17, 2022)  
an inference about the worker’s exposure to carbon monoxide from the evidence supporting that  
other staff at the school were also reporting similar symptoms typically associated with such  
exposure.  
[109] Additionally, I find the worker’s reported symptoms coincide with the timing of the  
HVAC malfunctions, which were first identified in early December 2017. There is no dispute  
that a mechanical failure was identified on the rooftop HVAC unit. On this matter, the Board’s  
OHOs advised that improper operation of heating components of an HVAC system can give rise  
to incomplete combustion of natural gas, which can give rise to elevated carbon monoxide  
levels in a workplace. Although there was no evidence that the mechanical failure of the rooftop  
HVAC system failed in a way that would give rise to carbon monoxide emission, this was  
possible, and aligned with the staff’s air quality complaints. I accept the OHOs’ findings and  
opinion on this matter, which were based on a thorough review of the claim file documents as  
well as their expertise on such issues.  
[110] I acknowledge that the OHOs’ opinion that it was “possible” that the rooftop HVAC malfunction  
gave rise to elevated carbon monoxide emission does not establish that this is actually what  
happened with any degree of certainty. However, when considered with the entirety of the  
evidence in this claim, whereby the worker’s reported symptoms are consistent with carbon  
monoxide poisoning and in keeping with the symptoms/complaints from other staff members  
around the same time, I consider it reasonable to find that it is at least as likely as not that the  
mechanical failure gave rise to carbon monoxide emission. As a result, I draw an inference  
about the worker’s exposure to carbon monoxide from the evidence supporting that there was  
an HVAC malfunction around the same time of her reported symptoms.  
[111] The evidence does not establish how much exposure to carbon monoxide resulted from the  
HVAC malfunctions. The employer did not conduct any air quality measurements around that  
time. As such, I cannot determine whether the levels of carbon monoxide exceeded the  
occupational exposure limits. However, I can infer from circumstantial evidence that the level of  
exposure was sufficient to have caused the worker’s symptoms and exceeded the exposure to  
carbon monoxide that people would normally encounter on a day-to-day basis. My findings that  
the HVAC malfunction likely raised the carbon monoxide emission in the school around the  
same time that the worker developed/reported her symptoms that are consistent with poisoning  
by carbon monoxide, provides sufficient basis to find that it was at least as likely as not that the  
worker was exposed to and suffered from acute poisoning by carbon monoxide sometime in  
late October/early November 2017 to mid-December 2017. In turn, I conclude that the  
requirements of Schedule 1, item #1(8) have been met. In accordance with section 137(2) it  
must be presumed that the poisoning was due to the nature of the worker’s employment, unless  
the contrary is proven.  
[112] I am mindful that the Board’s air quality inspection on December 18, 2017 did not find evidence  
of elevated levels of carbon monoxide in the metal shop or other areas of the school. The  
employer’s February and June 2018 air quality testing revealed that the levels of carbon  
monoxide were below the Board’s occupational exposure limits. However, I find that by the time  
23  
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WCAT Decision Number:  
A2100606 (August 17, 2022)  
these testing measures took place, the HVAC system defaults had already been repaired. As a  
result, I find that the air quality tests do not provide any useful information in deciding the  
worker’s carbon monoxide exposure around the time of the HVAC malfunctions prior to mid-  
December 2017. In other words, the air quality tests do not prove on a balance of probabilities  
that the worker was not exposed to carbon monoxide prior to December 18, 2017. As a result, I  
find that the presumption of work causation has not been rebutted by the evidence from the  
various air quality tests.  
[113] I also find that Dr. Raghukumar’s April 2019 opinion that there was no confirmed diagnosis of  
carbon monoxide poisoning does not rebut the presumption of work causation. I consider her  
opinion was limited to diagnostic considerations, which are not determinative of the matter (for  
reasons already discussed above). Dr. Raghukumar’s opinion did not take into account the  
legislative and policy provisions that set out the evidentiary basis upon which it can be  
established a worker suffered from carbon monoxide poisoning, even in the absence of a  
definitive diagnosis.  
[114] I do not consider there is any other relevant evidence in this claim that rebuts the presumption  
of work causation under Schedule 1. As a result, I find that the worker was likely exposed to and  
suffered from carbon monoxide poisoning sometime in late October/November to mid-  
December 2017 as a result of the HVAC malfunctions that were first identified in early  
December 2017. She is therefore entitled to the presumption of causation available under  
section 137(2) of the Act and Schedule 1. In turn, I find that for the specific time period in  
question, it must be presumed that the worker suffered from an occupational disease, being  
carbon monoxide poisoning, that was due to the nature of her employment.  
[115] On a final note, my decision is limited to consideration of whether the worker suffered from  
carbon monoxide poisoning as an occupational disease due to the nature of her employment,  
and what benefits may arise is beyond the scope of this appeal. That said, I merely note that it  
does not appear that during the specific time period in question, the worker was “disabled” from  
earning full wages as contemplated in section 136 of the Act. The evidence appears to suggest  
that she did not lose time from work until May 2018. Nonetheless, I make no formal ruling on  
this matter and leave it to the Board to determine the worker’s entitlement to benefits, if any,  
arising out of my decision.  
December 18, 2017 to May 30, 2018  
[116] I have already found that the rooftop HVAC malfunction was repaired soon after being first  
identified in early December 2017. This means that the rise in the carbon monoxide emission  
generated from the rooftop HVAC malfunction was no longer an issue by the time that the Board  
OHO visited the school to investigate the air quality complaints on December 18, 2017. In turn,  
this means that the basis upon which I accepted the worker’s claim for carbon monoxide  
poisoning for the time period prior to mid-December 2017, is not applicable to the consideration  
of the worker’s exposure beyond then. As a result, my analysis will focus on the worker’s  
exposure to products of combustion or other sources of carbon monoxide as a result of the  
24  
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WCAT Decision Number:  
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welding tasks/processes that took place in the metal shop from December 18, 2017 to May 30,  
2018.  
[117] I find the evidence on the whole, and in particular, the information documented in the OHOs’  
January 2019 investigation report, supports that the welding tasks/processes performed in the  
metal shop generated some carbon monoxide. The employer did not dispute this point. Rather,  
it argued that the worker was not exposed to toxic levels of carbon monoxide to have caused  
carbon monoxide poisoning.  
[118] On the whole, I find the evidence supports that effective December 18, 2017, the worker was  
not exposed to carbon monoxide beyond that people would normally encounter on a day-to-day  
basis, or that exceeded the exposure limits set out in the OHS Regulation. In deciding this, I  
note the Board’s December 18, 2017 air quality inspection revealed no evidence of elevated  
levels of carbon monoxide. I consider the Board OHO has some expertise in assessing indoor  
air quality for occupational exposures to various airborne substances including carbon  
monoxide. Additionally, the OHO’s findings are in keeping with the findings from the air quality  
tests undertaken by the employer in February 2018 and June 2018, which consistently recorded  
levels of carbon monoxide below the Board’s exposure limits.  
[119] I am mindful that the worker takes issue with the employer’s testing that took place in February  
2018 on the basis of the placement of the Q-track monitor in the welding bay. She argued that  
the monitoring equipment was 5 feet away from the aluminum foundry, and therefore too far to  
measure the exposure levels produced by that piece of equipment or welding processes. At the  
hearing, she testified that she did not stand in front of the welding machine for the entire class.  
Rather, she moved around from station to station.  
[120] A problem for the worker is that there is no persuasive evidence suggesting that the placement  
of the Q-track monitor did not accurately measure the carbon monoxide levels in the classroom  
overall. I have no basis to find that the Q-track testing only measured the carbon monoxide  
levels specific to the area in or around the welding bay where the monitor was placed. In the  
absence of any indication that the worker has some expertise on this subject matter, I do not  
accept her evidence that the Q-track testing produced inaccurate/unreliable results due to its  
placement in the classroom. Given that the test logged data for 3 consecutive days at  
120 second intervals, I am satisfied that the results provide an accurate measure of the carbon  
monoxide levels that the worker was exposed to while working in the metal shop.  
[121] The worker also argued that the February 2018 testing revealed carbon monoxide levels that  
exceeded the regulated exposure limits, which supported that she was exposed to toxic levels  
of carbon monoxide. I disagree with the worker, and find that none of the samples exceeded the  
occupational exposure limits set out in the OHS Regulation. It appears that her position is based  
on the acceptable indoor air quality levels developed by ASHRAE, which sets out the minimum  
requirements for optimal health and comfort inside buildings/office environments. However,  
I have no reason to apply the ASHRAE standards to the worker’s case. Having said that, even if  
I applied those standards, this would not change the outcome of the appeal. This is because out  
25  
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WCAT Decision Number:  
A2100606 (August 17, 2022)  
of the 1,440 samples, the carbon monoxide levels were recorded mostly at 0 ppm with a range  
between 0.1 and 2.9 ppm on the rare occasion. This falls below the ASHRAE standard of  
5 ppm. I acknowledge that on one occasion, the maximum level recording was documented at  
7.6 ppm; however, this went down to 0 ppm in the next sample (2 minutes later). I am not  
persuaded that this 2-minute interval over a 3-day time period provides sufficient basis to find  
the worker was exposed to carbon monoxide levels that exceeded the exposure limits.  
[122] I am also not persuaded by the worker’s argument that the June 2018 testing was invalid on the  
basis that the substitute teacher who wore the monitor was working on his own projects and  
letting the students do “whatever” they wanted in class. I interpret this to mean that the students  
were not using the welding equipment properly when the testing took place. However, the  
worker did not provide any evidence supporting her statements. I note that she was no longer  
working at the school when the June 2018 testing took place. She did not explain how she came  
to know what the teacher was doing during classroom hours. Additionally, I note the substitute  
teacher specifically documented the welding tasks performed by the students in each block  
during the 2 days of testing. I am not persuaded that he would have provided false information  
about the student’s tasks. Further, although the measurements spiked at the beginning and end  
of testing, I accept the employer’s OHS manager’s explanation that this was due to calibration of  
the monitor. The worker did not provide any contradictory evidence on this matter.  
[123] As support for her position that she was exposed to toxic levels of airborne substances  
(including carbon monoxide), the worker noted that in December 2017, the Board’s OHO found  
that the employer’s welding, cutting, and similar processes were not being carried out using  
adequate ventilation. She also argued that the March 2018 engineering report supported that  
the fumes were not being removed from the classroom. While there is no dispute that there  
were some issues with the ventilation system in the school, I do not agree with the worker that  
this means that no fumes were being removed and/or that she was inhaling all the fumes.  
Neither the Board OHO nor the engineering consultant suggested that was the case.  
Additionally, this matter was specifically addressed by the OHOs in their January 2019  
investigation report, and their findings/opinions do not support the worker’s position.  
[124] More specifically, the OHOs noted that despite the ventilation issues, there were exhaust fans  
and a general HVAC system in the metal shop. I accept their opinion that the low levels of  
carbon monoxide (and carbon dioxide) levels measured from the air quality testing supported  
that these ventilation systems were serving to remove contaminants from the work environment.  
The OHOs noted that while the exhaust ventilation system in the metal shop was determined to  
be less than optimal, ventilation gases are light and would have easily become entrenched in  
the ventilation flow created by the 3 exhaust fans. It was therefore unlikely that carbon  
monoxide (or carbon dioxide) levels would have approached or exceeded the respective  
exposure limits during typical student tasks. For these reasons, it was expected that the  
airborne levels of welding gases in the metal shop would have been very low despite the poor  
ventilation design.  
26  
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WCAT Decision Number:  
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[125] The OHOs also noted that there were 2 large canopy hood exhaust ventilation systems  
servicing both the forge and welding areas. In their opinion, while the canopy hood design was  
determined to be of a poor design for the scope of work, the exhaust fans were more or less  
appropriately sized for the scope and nature of the student centered tasks. Additionally, the  
employer took steps to restrict the use of certain equipment within the shop and/or put  
conditions on their use until such time that the recommended upgrades could be completed. As  
such, it was unlikely that welding fume and gas levels would have approached or exceeded the  
Board exposure limits for these substances. In the OHO’s opinion, it was unlikely that the  
worker was exposed to harmful levels of metal oxide fumes during her work in the metal shop.  
[126] Overall, I accept the OHOs’ opinion, which was based on a thorough review of the relevant  
claim file documents. In the absence of a persuasive opinion suggesting otherwise, I find the  
evidence supports the exhaust ventilation system, albeit less than optimal, and the poor design  
of the canopy hood, were nonetheless removing the welding gases and fumes in the metal  
shop. This does not support the worker’s position that she was exposed to toxic levels of carbon  
monoxide gases or fumes in her employment from mid-December 2017 onwards.  
[127] While not necessary to my decision, I also considered whether the worker’s ongoing symptoms  
supported a finding that she was exposed to toxic levels of carbon monoxide from mid-  
December 2017 onwards. A problem for the worker is that from December 18, 2017 to May 30,  
2018, it does not appear that she reported ongoing symptoms associated with carbon monoxide  
exposure to the employer. More specifically, there is no documentation of the worker reporting  
further headaches, nausea, fatigue, or dizziness during this time period. In my view, this lack of  
ongoing reported symptoms suggests that there was no further carbon monoxide exposure  
beyond mid-December 2017.  
[128] I acknowledge that on May 30, 2018, the worker sought medical attention from Dr. Hollman and  
reported ongoing symptoms. At the hearing, she testified that although some of the equipment  
in the metal shop was shut down in December 2017, she did not notice much difference in her  
symptoms. However, I have some difficulty accepting the worker’s testimony that she had  
ongoing symptoms related to carbon monoxide exposure beyond December 18, 2017 given the  
lack of documented complaints to the employer beyond that date (as discussed above). In  
addition to this, I find there is a significant gap in the medical evidence from December 18, 2017  
to May 30, 2018. This is particularly relevant given that on December 15, 2017, the worker was  
advised to return to the hospital when she was symptomatic so that further testing for carbon  
monoxide poisoning could be conducted. There is no indication that she returned to the hospital,  
which suggests a resolution of symptoms associated with carbon monoxide exposure by  
December 18, 2017. The worker did not address why she waited approximately 5½ months  
before visiting Dr. Hollman if she remained symptomatic.  
[129] Additionally, I find the worker did not lose time from work as a result of carbon monoxide  
exposure from mid-December 2017 to May 30, 2018, which is further support that  
her symptoms had resolved. In deciding this, I note that in her teleclaim application, the worker  
advised that she had not missed any time from work as a result of the indoor air quality issues  
27  
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WCAT Decision Number:  
A2100606 (August 17, 2022)  
at work. This was also documented in the employer’s report of injury. I acknowledge that in June  
2018, the worker told a Board officer that she missed some days from work beginning in  
January 2018. At the hearing, she testified that between September 2017 and May 30, 2018,  
she sporadically missed 4 or 5 days from work because she felt unwell. I am not persuaded by  
the worker’s evidence/testimony that she missed time from work due to symptoms associated  
with ongoing carbon monoxide exposure. I place more weight on the information documented in  
the worker’s and employer’s reports of injury to the Board, which were provided around the time  
that she actually stopped working.  
[130] At this juncture, I note there is no dispute that by December 18, 2017, the employer had shut  
down several welding equipment/processes in the metal shop classroom. This is relevant given  
the worker’s evidence that she became symptomatic when all the welding equipment was  
running in the metal shop simultaneously, as documented in the employer’s investigation report  
and hospital clinical records (as summarized above). In these circumstances, I consider it  
reasonable to find that the shutdown of some of the welding equipment/processes likely  
reduced the level of carbon monoxide generated in the metal shop, which likely explains, in part,  
the lack of ongoing complaints beyond December 18, 2017.  
[131] While the worker stopped working on May 30, 2018, I am not persuaded that this was due to  
any ongoing exposure to carbon monoxide. I find the evidence supports that the worker was  
trying to get pregnant around that time, and she was concerned about the air quality issues  
identified by the Board and engineer consultant. The June 4, 2018 health and safety meeting  
notes document the worker’s concerns about possible exposure to toxins given that she was  
trying to conceive. In addition to these issues, I find the evidence supports that the worker felt  
the employer was not taking her complaints seriously or responding to the ventilation issues in a  
timely manner. The claim file documents note her complaints in that regard, which includes her  
view that the employer was “sandbagging” the investigation. On the whole, I find the worker’s  
frustrations with the employer coupled with her concerns about possible exposure to  
reproductive toxins while trying to get pregnant were likely the reason that she sought medical  
attention and stopped working on May 30, 2018.  
[132] Overall, I find there is insufficient evidence to support the worker had symptoms consistent with  
carbon monoxide exposure beyond December 18, 2017. In turn, this further supports my finding  
that she was not exposed to toxic levels of carbon monoxide as a result of the welding  
tasks/processes that took place in the metal shop from December 18, 2017 to May 30, 2018.  
Summary  
[133] I find that it is at least as likely as not that the worker was exposed to and suffered from acute  
poisoning by carbon monoxide sometime in late October/early November 2017 to mid-  
December 2017, as a result of the HVAC malfunctions that were first identified at the school in  
early December 2017. She is therefore entitled to the presumption of causation available under  
section 137(2) of the Act and Schedule 1. In turn, I find that on or around late October/early  
28  
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WCAT Decision Number:  
A2100606 (August 17, 2022)  
November 2017 to mid-December 2017, the worker suffered from carbon monoxide poisoning  
as an occupational disease that was due to the nature of her employment.  
[134] I also find that the HVAC malfunctions were fully repaired and no longer an issue effective  
mid-December 2017. The weight of the evidence supports that the worker not exposed to  
products of combustion or other sources of carbon monoxide as a result of the welding  
tasks/processes that took place in the metal shop from December 18, 2017 to May 30, 2018.  
[135] The worker’s appeal is allowed on this issue, in part.  
Are the worker’s uterine fibroid and/or miscarriages in 2018 occupational diseases due to  
the nature of her employment?  
[136] Neither uterine fibroids nor miscarriages are recognized as occupational diseases under  
Schedule 1 or by regulation of general application.  
[137] Pursuant to policy item C4-25.10 of the RSCM II, a disease that is not otherwise designated by  
the Board as an occupational disease may be recognized by order dealing with a specific case if  
the merits and justice of an individual claim for such a disease warrant its recognition as an  
occupational disease. Such recognition is limited to the specific facts of that case. This means  
that I must consider whether the worker’s uterine fibroid and/or miscarriages should be  
designated as an occupational disease by order dealing with a specific case. In deciding this,  
the analysis requires consideration of whether the disease is due to the nature of the worker’s  
employment. As noted earlier, the occupational disease is due to the nature of the worker’s  
employment if the employment was of causative significance in producing the disease.  
Causative significance means more than a trivial or insignificant aspect.  
Uterine Fibroid  
[138] The worker’s position is that her uterine fibroid was caused by her exposure to reproductive  
toxins including carbon monoxide, carbon dioxide, and various heavy metals.  
[139] I have already found that the worker suffered from acute poisoning by carbon monoxide in or  
around late October/November to mid-December 2017 as a result of the rooftop HVAC  
malfunction at the school. I must therefore consider this in my adjudication of the issue.  
[140] Based on the OHOs’ investigation report of January 2019, I also find that the worker was not  
exposed to harmful levels of welding gases (including carbon monoxide and carbon dioxide) or  
metal oxide fumes as a result of the welding tasks/processes that took place in the metal shop. I  
have already summarized the OHOs’ investigation report in detail above, and will not repeat the  
information in detail again. I have also addressed the OHOs’ findings and opinions in my  
analysis in relation to the worker’s carbon monoxide exposure (paragraphs 124 to 126). I  
consider that analysis applies to the consideration of this issue. More specifically, for the same  
reasons discussed above, I accept the OHOs’ opinions that the airborne levels of welding gases  
29  
150, 4600 Jacombs Road, Richmond, B.C. V6V 3B1  
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WCAT Decision Number:  
A2100606 (August 17, 2022)  
(carbon monoxide and carbon dioxide) and metal oxide fumes would have been very low  
despite the ventilation issues identified by the Board OHO in December 2017 and the engineer  
consultant in March 2018. I consider this is in keeping with the findings from the air quality  
testing that took place in December 2017, February 2018, June 2018, and November 2018,  
which did not find any evidence of elevated levels of carbon monoxide or carbon dioxide in the  
metal shop.  
[141] I also accept the OHO’s opinion documented in the March 2019 investigation report, whereby  
he noted that it was unlikely the worker was exposed to harmful levels of welding fume  
contaminants (heavy metals) during her work in the metal shop. I note the OHO’s opinion was  
based on the relevant claim file documents, which included a review of the employer’s exposure  
control plan for welding fumes that listed all the products used in the metal shop, as well as  
material safety data sheets in relation to those products. The OHO documented all the metals  
found in the products used in the metal shop and specifically addressed the worker’s concerns  
about her exposure to cadmium. Overall, I find the OHO’s opinion was well-reasoned and  
persuasive. For these reasons, and given his expertise on the subject matter, I place some  
weight on his opinion in adjudicating the issue on appeal.  
[142] I acknowledge that Dr. Hollman’s May 2018 and August 2018 medical reports document  
“possible recurrent” carbon dioxide poisoning and “previous poisoning from carbon dioxide.”  
However, I have already found that Dr. Hollman’s diagnoses were based entirely on the  
worker’s description of her symptoms and the worker’s opinion that she was exposed to toxic  
levels of carbon dioxide at work, rather than Dr. Hollman’s own independent observations of the  
worker’s condition/symptoms. For the same reasons discussed earlier, I place no weight on  
Dr. Hollman’s carbon dioxide diagnosis documented in her medical reports.  
[143] While I have found that the worker was not exposed to harmful levels of carbon monoxide,  
carbon dioxide, metal oxide fumes, or heavy metal contaminants/fumes as a result of the  
welding tasks/processes that took place in the metal shop, this is not to say that she was not  
exposed to any levels of welding gases or fumes. Speaking generally, I interpret the OHOs’  
findings and opinions to mean the worker likely experienced exposure to low levels of welding  
gases and fumes/contaminants (heavy metals) through her teaching work in the metal shop. In  
these circumstances, I have considered whether such low levels of exposure, in addition to the  
acute poisoning by carbon monoxide in or around late October/November to mid-December  
2017 (as a result of the rooftop HVAC malfunction) were of causative significance in producing  
the worker’s uterine fibroid. I consider this issue is medical in nature and requires medical  
expertise.  
[144] Turning to the medical evidence, I find it particularly telling that the worker sought medical  
attention from various practitioners/specialists in relation to her uterine fibroid and fertility issues,  
none of whom provided opinions in support of her position. The medical reports documented the  
worker’s repeated concerns about an occupational link between her uterine fibroid/fertility issues  
and exposure to carbon monoxide/dioxide and heavy metals. Despite this, Dr. Wroz advised the  
worker that there was no evidence to support her theory on reproductive toxins. This is in  
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Tel: (604) 664-7800 | 1-800-663-2782  
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WCAT Decision Number:  
A2100606 (August 17, 2022)  
keeping with what the worker was subsequently told by Drs. Bediway and Yupze. I note that  
neither Dr. Hollman nor Dr. Adams supported the worker’s position regarding an occupational  
link either.  
[145] I am mindful that the worker advised a Board officer that Dr. Bediway told her that the medical  
system did not allow him to comment on a connection between her fibroid and heavy metal  
exposure. He apparently told her that he could not comment on the cause of her hormone  
issues, which were described as “out of whack” and that he could only treat her symptoms. It is  
unclear if the worker was suggesting that Dr. Bediway felt there was an occupational link, but  
could not comment on it. Nonetheless, even if this was the worker’s suggestion, I find that her  
statements represent hearsay evidence, and I place no weight on her account of what  
Dr. Bediway told her. Irrespective of that, I consider it reasonable to find the worker’s statements  
are actually inaccurate because Dr. Bediway’s medical reports state that the worker’s hormone  
levels/ovarian screen were normal. There is no basis to find that he felt the worker’s hormones  
were “out of whack” and/or related to her exposure at work, as she reported to the Board.  
[146] For similar reasons, I place no weight on the worker’s statements to the Board about  
Dr. Spooner’s opinion that her fibroid and inability to conceive were related to her exposure to  
heavy metals at work. While Dr. Spooner administered urine element testing on the worker, his  
corresponding report did not indicate there was an occupational link in the worker’s case. I note  
that the Board specifically requested Dr. Spooner for an opinion on the cause of the worker’s  
uterine fibroid/fertility issues, but he did not submit anything to support the worker’s position  
(despite being aware of Dr. Raghukumar’s contradictory opinion refuting claim acceptance).  
[147] The only other relevant medical opinion to consider is from Dr. Raghukumar, which refutes a  
causal link between the worker’s exposure and uterine fibroid. I disagree with the worker that  
Dr. Raghukumar’s opinion was based on an inaccurate understanding of what she was exposed  
to. I note that Dr. Raghukumar’s opinion is quite lengthy and detailed. She summarized the  
worker’s exposure history, taking into account the information documented in the OHOs’  
investigation reports. These reports addressed the worker’s potential exposure to welding  
gases/fumes from September 2017 to May 30, 2018, and specifically considered her exposure  
due to the fan failure identified in October 2017, the rooftop HVAC malfunction identified in  
December 2017, general exhaust ventilation issues in the metal shop as identified by the Board  
OHO in December 2017 and the engineer consultant in March 2018. In these circumstances, I  
am satisfied that Dr. Raghukumar had an accurate understanding of the worker’s exposure. I  
consider her opinion is directly on point, and in the absence of a persuasive contradictory  
opinion stating otherwise, I place some weight on Dr. Raghukumar’s opinion in adjudicating the  
issue on appeal.  
[148] I acknowledge the worker’s research that addressed potential occupational links between  
exposure to welding gases/fumes/heavy metals and reproductive/fertility issues. However, the  
fact that an occupational link “may” exist does not automatically mean this is the scenario in the  
worker’s case. The worker’s research does not address her specific levels of exposure in her  
specific high school teaching setting. In the absence of any research supporting a link between  
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Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
the worker’s specific levels of exposure at her school (as I have found) and the uterine fibroid, I  
find the worker’s research does not assist her position. The fact that the worker believes that her  
occupational exposure caused her uterine fibroid is also not sufficient basis to accept her claim.  
The worker does not have the medical expertise to provide an opinion on this matter.  
[149] In summary, I find the worker’s exposure to low levels of welding gases and welding  
fumes/contaminants through her teaching work in the metal shop, as well as her acute  
poisoning by carbon monoxide in or around late October/November to mid-December 2017 (as  
a result of the rooftop HVAC malfunction) were not of causative significance in producing her  
uterine fibroid. As a result, I find the worker’s uterine fibroid was not due to the nature of her  
employment. The worker’s claim remains denied for this condition.  
Miscarriages  
[150] The worker argued that her miscarriages in 2018 were due to her exposure to reproductive  
toxins including carbon monoxide, carbon dioxide, and various heavy metals.  
[151] A problem for the worker is that the weight of the evidence does not support that she actually  
had any miscarriages in 2018. In deciding this, I note there are inconsistencies in the worker’s  
evidence about how many miscarriages she had and when they occurred. The worker did not  
report any miscarriages when she filed her teleclaim application in May 2018. In June 2018, she  
told a Board officer that she had 2 miscarriages since she started working at the school (which  
was in 2016). In September 2018, she told the Board officer that she suffered 3 miscarriages  
due to her work exposure. At the hearing, the worker testified that she had 2 miscarriages  
between January 2018 and April/May 2018, and that she had no prior miscarriages. However,  
she did not provide any details about her miscarriages, or address the inconsistencies  
documented in the claim file documents at the hearing. She also did not address the lack of  
reference to miscarriages in the medical reports (as discussed below). On the whole, I found the  
worker’s testimony on this matter was very brief and not compelling.  
[152] I also consider it problematic that none of the medical reports document the worker’s  
miscarriages. Between May 30, 2018 and July 17, 2019, the worker was assessed by her family  
physician, 2 gynecologists, a fertility specialist, and an endocrinology/fertility specialist with an  
expertise in heavy metal exposure and infertility. Despite this, none of them refer to the worker  
having experienced any miscarriages. In fact, in November 2018, Dr. Bediway documented the  
worker’s past medical/gynecological history in great detail without mentioning a miscarriage.  
Given that the worker was being assessed for reproductive/infertility issues, I would have  
expected some mention of the miscarriages. I have no reason to believe that all of the worker’s  
physicians/specialists would have failed to document this relevant history in their clinical  
records/reports. In fact, I note that in March 2019, Dr. Yupze specifically noted that the worker  
advised that her partner had a son from a previous relationship, but that she had never been  
pregnant. This is in direct conflict with the worker’s evidence/testimony that she had  
experienced miscarriages in 2018. In the absence of any evidence suggesting that Dr. Yupze’s  
account of what the worker reported was inaccurate, I find that the worker never been pregnant  
32  
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Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
before her consultation with Dr. Yupze. In turn, this supports a finding that she had not suffered  
any miscarriages in 2018.  
[153] Having said that, even if I am wrong and the worker had miscarriages in 2018, this would not  
change the final outcome of the appeal. In the end, I find the medical evidence does not support  
an occupational link between the worker’s exposure to welding gases/fumes and her  
miscarriages. As discussed earlier, none of the worker’s physicians provided opinions  
supporting the worker’s position on this matter. In fact, in September 2018, the worker told a  
Board officer that she was looking for a new gynecologist because Dr. Wroz told her that the  
work environment did not cause her miscarriages. This refutes the worker’s position.  
[154] Additionally, Dr. Bediway recommended the worker undergo surgery to have her uterine fibroid  
removed because it increased the likelihood of miscarriage. I interpret this to mean there is a  
direct link/biological plausibility between uterine fibroids and miscarriages. However, given my  
finding that the worker’s uterine fibroid is not compensable, it then follows that any consequence  
of the uterine fibroid (miscarriage) is also not compensable.  
[155] I have already addressed Dr. Spooner’s findings above and will not repeat my analysis. For the  
same reasons discussed earlier, I consider his clinical records/report do not assist in the  
consideration of the issue on appeal.  
[156] In summary, I find the evidence does not support the worker had any miscarriages in 2018. In  
the alternative, if the worker had miscarriages, I find that her exposure to low levels of welding  
gases/fumes and/or heavy metals through her teaching work in the metal shop, as well as her  
acute poisoning by carbon monoxide in or around late October/November to mid-December  
2017 (as a result of the rooftop HVAC malfunction) were not of causative significance in  
producing her miscarriages. As a result, I find that the miscarriages were not due to the nature  
of her employment. The worker’s claim remains denied for this condition.  
[157] The worker’s appeal is denied on this issue.  
Conclusion  
[158] The worker’s appeal is allowed, in part, and the review officer’s decision is varied, in part. More  
specifically, I find as follows:  
Sometime in late October/November 2017 to mid-December 2017, the worker suffered from  
acute poisoning by carbon monoxide as a result of the rooftop HVAC malfunction that was  
first identified in early December 2017. As such, the evidence supports that the worker  
suffered from carbon monoxide poisoning as an occupational disease that was due to the  
nature of her employment. I also find that the worker was not exposed to toxic levels of  
carbon monoxide from mid-December 2017 onwards. As discussed in paragraph 115  
above, the evidence appears to suggest that the worker did not lose time from work until  
33  
150, 4600 Jacombs Road, Richmond, B.C. V6V 3B1  
Tel: (604) 664-7800 | 1-800-663-2782  
Fax: (604) 664-7898 | wcat.bc.ca  
WCAT Decision Number:  
A2100606 (August 17, 2022)  
May 2018. Nonetheless, I make no formal ruling on this matter and leave it to the Board to  
determine the worker’s entitlement to benefits, if any, arising out of my decision.  
The worker’s uterine fibroid and miscarriages in 2018 are not occupational diseases due to  
the nature of her employment.  
[159] The worker did not request reimbursement of any expenses related to this appeal, and none are  
apparent to me. As such, I make no order for reimbursement of any appeal expenses.  
Simi Saini  
Vice Chair  
34  
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