Heat-related illness among workers in British Columbia, Canada: Extreme hot weather in 2021 compared to 2001–2020

OBJECTIVES: British Columbia (BC), Canada, experienced an unprecedented summer with record-breaking high temperatures in 2021. Yet the health impact has not been examined in occupational settings. This study aimed to characterize occupational heat-related illness (HRI) among BC workers estimated by incidence rates and associations between heatwaves and HRI, compare risks from 2021 and prior summers of 2001–2020, and assess differential impacts on worker groups by demographics and occupations. METHODS: We identified HRI from workers’ compensation claims that occurred between June and August from 2001–2021 in BC. Incidence rates were calculated using working population estimates from Statistics Canada’s Labour Force Survey. A time-stratified case-crossover design with conditional Poisson regression was used to examine the impact of heatwaves on occupational HRI. All analyses were stratified by year (2021 versus 2001–2020), age, sex, and occupation. RESULTS: Of the 521 claims identified, 107 (21%) occurred in 2021. Incidence rates for 2021 and prior summers were 3.97 [95% confidence interval (CI) 3.26–4.80] and 0.93 (95% CI 0.85–1.03) claims per 100 000 workers, respectively. This difference represents a 327% increase. Rates were higher in health occupations in 2021 versus 2001–2020. During 2001–2021, the risk of HRI during heatwave days was 4.33 (95% CI 2.98–6.27) times that during non-heatwave days, and the risk was higher among middle-aged workers and workers in trades, transport, and equipment operations. The 2021 heatwaves had greater impact on younger and female workers than those from prior summers. CONCLUSIONS: Heat is a crucial workplace hazard. Prevention strategies should prioritize at-risk workers and not be limited to heatwaves.