Emergency department visits associated with wildfire smoke events in California, 2016–2019

“Air That Once Was Breath” Part 2: Wildfire Smoke and Airway Disease – “Climate Change, Allergy and Immunology” Special IAAI Article Collection: Collegium Internationale Allergologicum Update 2023

“…Most investigations on the health effects during or immediately after wildfire smoke exposure focused on increased healthcare seeking and hospitalizations due to acute symptoms. These revealed that asthma exacerbations, bronchitis, bronchopneumonia, and COPD symptoms were the most common [6, [16][17][18][19][20][21]. A positive association was found between acute healthcare utilization in asthma and COPD, with either levels of PM10 [22], PM2.5 [17,20,23], or both [13,18,24].…”

“…These revealed that asthma exacerbations, bronchitis, bronchopneumonia, and COPD symptoms were the most common [6, [16][17][18][19][20][21]. A positive association was found between acute healthcare utilization in asthma and COPD, with either levels of PM10 [22], PM2.5 [17,20,23], or both [13,18,24]. It is interesting to note that wildfire smoke PM2.5 levels are also associated with hospital admissions for congestive heart failure [25].…”

“…This approach controls for time-invariant confounders that vary spatially but not those confounders that vary temporally (i.e., in this study, lag 0 means no delay in the wildfire smoke effect; lag 1 would be 1 day delay, etc.). In a more recent study, Chen and colleagues [20] examined wildfire smoke events (PM2.5 threshold = 13.5 μg/m 3 ) and emergency department visits for respiratory, cardiovascular, diabetes, and mental health outcomes in California between 2016 and 2019. They showed that wildfire smoke events significantly associated with all respiratory diseases at lag 1 (14.4%, 95% CI: 6.8, 22.5), asthma at lag 0 (57.1% [44.5, 70.8]), chronic lower respiratory disease at lag 0 (12.7% [6.2, 19.6]), and all cardiovascular diseases at lag 10 with mixed results for mental health outcomes.…”

“…They showed that wildfire smoke events significantly associated with all respiratory diseases at lag 1 (14.4%, 95% CI: 6.8, 22.5), asthma at lag 0 (57.1% [44.5, 70.8]), chronic lower respiratory disease at lag 0 (12.7% [6.2, 19.6]), and all cardiovascular diseases at lag 10 with mixed results for mental health outcomes. The authors suggest that in comparison with airway disease, cardiovascular impacts may be delayed in response to wildfire smoke exposure [20]. The pathogenic reasons for this are unclear.…”

“…Psychosocial stressors have been noted to be pronounced in vulnerable populations. In a comprehensive study spanning the wildfire seasons from 2016 to 2019 in California, Chen et al [20] examined the associations between smoke events and emergency department visits for various health outcomes. They measured daily wildfire-specific PM2.5 concentrations and defined "smoke events" as air basin-days where PM2.5 levels exceeded the 98th percentile (threshold: 13.5 μg/m³).…”