Changes in lung function and fractional exhaled nitric oxide across wildfire seasons in the wildland firefighter exposure and health effect (WFFEHE) study.

INTRODUCTION

Long-term pulmonary effects of wildland firefighting are unclear even though lung function declines have been observed following wildfire season and firefighting shift.

METHODS

Spirometry and airway inflammation indicated as fractional exhaled nitric oxide (FeNO) were measured among 152 wildland firefighters (WFFs) at the beginning (pre-season, April & May) and end (post-season, September & October) of the 2018 and/or 2019 wildfire seasons and among 19 WFFs at across 3 days of firefighting during a 2019 mid-season wildfire deployment.

RESULTS

Overall peak expiratory flow (PEF) and percent of predicted PEF (PEF%) significantly decreased across fire season when 2018 and 2019 measurements were combined (-0.15 ± 0.07 L/s, p = 0.04; -1.87 ± 0.71%, p = 0.01; respectively), more so due to 2018 declines. PEF% and percent of predicted forced vital capacity (FVC%) significantly improved between 2018 post-season and 2019 pre-season (i.e., off-season) (3.08 ± 1.26%, p = 0.02; 0.99 ± 0.41%, p = 0.02; respectively). FVC and FVC% significantly decreased across a firefighting shift on the first day of wildfire deployment (-0.12 ± 0.03 L, p < 0.01; -2.35 ± 0.64%, p < 0.01). FeNO significantly decreased across the 2018 and 2019 fire seasons (p < 0.01) and significantly increased during the off-season (p < 0.01). FeNO also showed statistically significant cross-shift decreases on the second day of wildfire deployment (-3.50 ± 0.95 ppm, p < 0.01).

CONCLUSIONS

Seasonal wildland firefighting were associated with decreases in lung function and FeNO as well as increases in respiratory symptom score in this cohort. While lung function recovered during the off-season among the WFFs, the results suggest a need for longer-term studies to determine the impact of chronic wildland firefighting on pulmonary health.