Respiratory Injuries among California Career Firefighters, 2000-2019.

Rationale: The association between firefighting exposure and respiratory injuries remains poorly quantified, despite the inhalational hazards of firefighting.

Objectives: To describe respiratory injury rates among California firefighters between 2000 to 2019 demographically, temporally, and geographically.

Methods: Using data from the California Workers' Compensation Information System from 2000 to 2019, we analyzed California firefighter workers' compensation claims for respiratory injuries from 2000 to 2019. We identified firefighter respiratory claims using nature of injury codes, injury description keywords, and International Classification of Diseases Ninth or Tenth revision codes. We estimated California firefighter employment totals using the American Community Survey.

Measurements: We calculated respiratory injury rates, rate ratios, and their associated confidence intervals by age and injury date and location.

Main results: We identified 3,431 respiratory injury claims between 2000 to 2019 (478 respiratory claims/100,000 California career firefighters, 90% CI: 432-534) and the respiratory injury rate remained unchanged. Firefighters aged 50 to 59 years had a higher risk of respiratory injuries compared to those aged 18 to 29 years (rate ratio=1.7, 90% CI: 1.6-1.8). Firefighters during wildfire season months had significantly more respiratory injuries than during non-wildfire season months. From 2000 to 2019, firefighter's respiratory injury rate in rural and small/medium metro counties increased significantly, while firefighter's respiratory injury rate in large metro counties decreased significantly.

Conclusions: Older firefighters, firefighters during wildfire season, and those in rural and small/medium metro counties may be at higher risk of respiratory injury, based on our large-scale, multi-year surveillance study among career California firefighters.