Exposure to extreme heat among workers in British Columbia

Extreme heat is becoming a high-risk hazard for the province of British Columbia (BC). From 2018 to 2022, there were 115 days when one or more health regions in BC were under heat warnings. As average temperatures in BC rise, extreme heat events will occur more frequently and for longer durations. The absence of sufficient Canadian data linking heat exposure among workers remains a significant knowledge gap. Therefore, the objectives of this thesis are: 1) Estimate the prevalence of heat exposure for workers by occupation, industry, and BC region. 2) Estimate the level of exposure to heat placing workers at risk of heat-related illnesses (HRIs) for workers by occupation, industry, and BC region (where possible). A modified mixed methods approach utilizing published and grey literature, occupational exposure estimates, key informant interviews, census data, and climate data was used to achieve the objectives of this thesis. This study identified over 350,000 workers in BC as exposed to hazardous levels of heat. Hazardous heat refers to the combination of environmental and metabolic heat exposures that exceed a worker’s capacity to thermoregulate, increasing the potential for heat-related illness. Our findings further indicate that construction trade helpers and labourers were the largest exposed group across BC. Additionally, boilermakers and miners are at the highest risk of exposure to hazardous levels of heat. We found that indoor workers make up a large proportion of exposed workers, suggesting that there is a broader range of occupations that may still experience meaningful heat exposure despite lower levels of outdoor work. These estimates tell us the aspects of a job that can put individuals at a higher risk of exposure to hazardous heat, allowing us to tailor future messaging and strategies to better recommend health and safety policies for BC workers. As HRIs are largely preventable, workers classified as exposed at any risk level warrants consideration. The findings from this thesis have important implications for the prevention and mitigation of hazardous heat exposure among BC workers.