Cardiopulmonary Effects of Fine Particulate Matter Exposure among Older Adults, during Wildfire and Non-Wildfire Periods, in the United States 2008–2010

Abstract

Background:The effects of exposure to fine particulate matter (PM2.5) during wildland fires are not well understood in comparison with PM2.5 exposures from other sources.Objectives:We examined the cardiopulmonary effects of short-term exposure to PM2.5 on smoke days in the United States to evaluate whether health effects are consistent with those during non-smoke days.Methods:We examined cardiopulmonary hospitalizations among adults ≥65 y of age, in U.S. counties (n=692) within 200km of 123 large wildfires during 2008–2010. We evaluated associations during smoke and non-smoke days and examined variability with respect to modeled and observed exposure metrics. Poisson regression was used to estimate county-specific effects at lag days 0–6 (L0–6), adjusted for day of week, temperature, humidity, and seasonal trend. We used meta-analyses to combine county-specific effects and estimate overall percentage differences in hospitalizations expressed per 10-μg/m3 increase in PM2.5.Results:Exposure to PM2.5, on all days and locations, was associated with increased hospitalizations on smoke and non-smoke days using modeled exposure metrics. The estimated effects persisted across multiple lags, with a percentage increase of 1.08% [95% confidence interval (CI): 0.28, 1.89] on smoke days and 0.67% (95% CI: −0.09, 1.44) on non-smoke days for respiratory and 0.61% (95% CI: 0.09, 1.14) on smoke days and 0.69% (95% CI: 0.19, 1.2) on non-smoke days for cardiovascular outcomes on L1. For asthma-related hospitalizations, the percentage increase was greater on smoke days [6.9% (95% CI: 3.71, 10.11)] than non-smoke days [1.34% (95% CI: −1.10, 3.77)] on L1.Conclusions:The increased risk of PM2.5-related cardiopulmonary hospitalizations was similar on smoke and non-smoke days across multiple lags and exposure metrics, whereas risk for asthma-related hospitalizations was higher during smoke days. https://doi.org/10.1289/EHP3860

Particulate matter and emergency visits for asthma: a time-series study of their association in the presence and absence of wildfire smoke in Reno, Nevada, 2013-2018

“…Despite removing wildfire days with extremely high PM2.5 concentrations, our results were similar to those of Deflorio-Barker et al [12], Reid et al [13], and Delfino et al [14], who all found that PM2.5 had a stronger association with asthma visits or hospitalizations during wildfire periods than during nonwildfire periods. We thus showed that the stronger associations of wildfire PM with asthma visits found in these studies cannot be solely attributed to differences in the concentration of wildfire PM and nonwildfire PM.…”

“…Our study used models very similar to those of Deflorio-Barker et al [12], Reid et al [13], and Delfino et al [14], which also included an interaction term between PM and an indicator for days affected by wildfire smoke. However, a key difference in our study is that we excluded wildfire days where PM2.5…”

“…We also report this change as a percent: (exp( 2 ) − 1) × 100. To estimate the variance of 1 + 2 , we used the standard formula for the variance of a linear combination of random variables, similar to Deflorio-Barker et al [12].…”

Mapping Modeled Exposure of Wildland Fire Smoke for Human Health Studies in California

“…A national study showed via principal component analyses that several vulnerability factors similar to those for general air pollution were relevant for fire-PM 2.5 ; specifically, factors included age (e.g., those >65 years); adults with respiratory disease (e.g., COPD and asthma); adults with hypertension, obesity and diabetes; children with asthma; and economic deprivation [35]. Age may also be a factor contributing to a population's susceptibility [36][37][38][39][40].…”

The Associations Between Clinical Respiratory Outcomes and Ambient Wildfire Smoke Exposure Among Pediatric Asthma Patients at National Jewish Health, 2012–2015

“…Looking specifically at asthma, wildfire smoke has been linked to increases in severe asthma-related outcomes such as emergency department visits (B. L. Alman, 2014;Breanna L. Alman et al, 2016;Gan et al, 2017;Haikerwal et al, 2016;Hutchinson et al, 2018;Kolbe & Gilchrist, 2009;Prevention, 1999;Rappold et al, 2011), overall hospital visits (Churches & Corbett, 1991;Duclos et al, 1990;Gan et al, 2017;Johnston et al, 2002;Prevention, 1999;Reid, 2014), and emergency medication use (Caamano-Isorna et al, 2011;Elliott et al, 2013;Tse et al, 2015). Indeed, Deflorio-Barker et al recently found that asthmarelated hospitalizations among elderly Americans were more sensitive to ambient PM 2.5 on smoke days than on nonsmoke days (DeFlorio-Barker et al, 2019). However, there has been limited research relating wildfires to less-severe asthma outcomes.…”