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

Abstract

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.

Keywords: epidemiology; occupational health; respiratory function tests.

Figure 1.

Flowchart of participants Abbreviations: WTC=World Trade Center

Figure 2a:

Differences in absolute FEV₁ for exposures within 3-months to 12-years prior to pulmonary function tests Unadjusted (♦) and adjusted (○) for age, race/ethnicity, height, smoking, and weight; Change is presented in mL FEV₁ per 1000 kg of particle exposure (P). Abbreviations: FEV₁=One-second Forced Expiratory Volume Figure 2b. Differences in absolute FEV₁ for exposures within 3-months to 12-years prior to pulmonary function tests by time of arrival at WTC disaster site Arrived at the World Trade Center site between 9/11/2001–9/12/2001 (♦) Arrived at WTC site after 9/12 (○) All models control for age, race/ethnicity, height, smoking, and weight. Change is presented in mL FEV₁ per 1000 kg of particle exposure (P) Abbreviation: FEV₁=One-second Forced Expiratory Volume