Abstract
BACKGROUND: Firefighters have a higher rate of heat-related illness (HRI) compared to other occupations. Given the changing climate, firefighters' risk of occupational HRI merits attention. Therefore, we aimed to identify demographic, temporal, and geographic risk factors associated with occupational HRI in California firefighters between 2001 and 2020. METHODS: Within the California Workers' Compensation Information Systems (WCIS), we identified firefighters from 2001 to 2020 using industry and class codes and assigned occupation titles using the NIOSH Industry and Occupation Computerized Coding system (NIOCCS). HRI claims among firefighters were identified using International Classification of Diseases (ICD) Ninth or Tenth revision codes, WCIS nature and cause of injury codes, and keywords. We calculated HRI incidence rates adjusted by sex, age, year, and county. Estimates of California firefighter employment were obtained from the American Community Survey. RESULTS: We identified 2185 firefighter HRI claims between 2001 and 2020 (305.5 claims/100,000 firefighters, 90% CI: 278.7-740.7). Firefighters aged 18 to 29 years had a statistically significant higher risk of HRI compared to those aged 40 to 49 years (rate ratio = 3.5, 90% CI: 3.1-3.9). The HRI rate increased over time, and the risk from 2016 to 2020 was 1.8 times higher than it was from 2001 to 2005 (90% CI: 1.7-1.9). Northern California counties, including Shasta (2313.9) and Sacramento (1772.1), had the highest HRI rates. CONCLUSIONS: Firefighters in certain demographic groups and northern California counties were at highest risk of HRI. With rising temperatures and larger wildfires, additional prevention efforts are needed to reduce HRI in California firefighters.