Wildfire smoke exposure and persistent respiratory symptoms and illness: a retrospective cohort study

BACKGROUND: Wildfire smoke is a growing public health hazard yet there is limited evidence on its intermediate or long-term respiratory health effects. Studying the association between wildfire smoke exposure and indicators of impaired respiratory health such as persistent respiratory illness and respiratory symptoms can help elucidate the associated risk of developing chronic lung disease. We sought to determine whether wildfire smoke exposure is associated with medically-attended respiratory illness (MARI) and respiratory symptoms persisting beyond the acute wildfire period. METHODS: ) exposure during a wildfire, estimated based on home and evacuation locations. The primary outcomes were respiratory illness requiring medical attention (MARI) at least one month after the wildfire and any respiratory symptom ("asthma attack," bronchitis, cough, respiratory infection, or wheezing) that persisted to the time of the survey (mean 8.5 months after wildfire). RESULTS: (EPA threshold for very unhealthy or hazardous air quality) was associated with an 11% increased risk of future severe MARI leading to emergency room visit or hospitalization (RR 1.11, 95% CI 1.02 - 1. 20, p=0.018). CONCLUSIONS: levels are associated with increased risk of ongoing respiratory morbidity and emergency healthcare utilization in the adult general population.