Association of firefighting exposures with lung function using a novel job exposure matrix (JEM)

OBJECTIVES: Characterisation of firefighters' exposures to dangerous chemicals in smoke from non-wildfire incidents, directly through personal monitoring and indirectly from work-related records, is scarce. The aim of this study was to evaluate the association between smoke particle exposures (P) and pulmonary function. METHODS: The study period spanned from January 2010 through September 2021. Routine firefighting P were estimated using fire incident characteristics, response data and emission factors from a novel job exposure matrix. Linear mixed effects modelling was employed to estimate changes in pulmonary function as measured by forced expiratory volume in one second (FEV1). Models controlled for age, race/ethnicity, height, smoking and weight. RESULTS: Every 1000 kg P was associated with 13 mL lower FEV1 (β=-13.34; 95% CI=-13.98 to -12.70) over the entire 12-year follow-up period. When analysing exposures within 3 months before PFT measurements, 1000 kg P was associated with 27 mL lower FEV1 (β=-26.87; 95% CI=-34.54 to -19.20). When evaluating P estimated within 3 months of a pulmonary function test (PFT), stronger associations were observed among those most highly exposed to the World Trade Center (WTC) disaster (β=-12.90; 95% CI=-22.70 to -2.89); the association of cumulative exposures was similar for both highly and less highly exposed individuals. DISCUSSION: Smoke particle exposures were observed to have modest short-term and long-term associations with pulmonary function, particularly in those who, previously, had high levels of WTC exposure. Future work examining the association between P and pulmonary function among non-WTC exposed firefighters will be essential for disentangling the effects of ageing, routine firefighting and WTC exposures.