Short-term exposure to wildfire-related PM2.5 increases mortality risks and burdens in Brazil

Abstract

To assess mortality risks and burdens associated with short-term exposure to wildfire-related fine particulate matter with diameter ≤ 2.5 μm (PM2.5), we collect daily mortality data from 2000 to 2016 for 510 immediate regions in Brazil, the most wildfire-prone area. We integrate data from multiple sources with a chemical transport model at the global scale to isolate daily concentrations of wildfire-related PM2.5 at a 0.25 × 0.25 resolution. With a two-stage time-series approach, we estimate (i) an increase of 3.1% (95% confidence interval [CI]: 2.4, 3.9%) in all-cause mortality, 2.6% (95%CI: 1.5, 3.8%) in cardiovascular mortality, and 7.7% (95%CI: 5.9, 9.5) in respiratory mortality over 0–14 days with each 10 μg/m3 increase in daily wildfire-related PM2.5; (ii) 0.65% of all-cause, 0.56% of cardiovascular, and 1.60% of respiratory mortality attributable to acute exposure to wildfire-related PM2.5, corresponding to 121,351 all-cause deaths, 29,510 cardiovascular deaths, and 31,287 respiratory deaths during the study period. In this study, we find stronger associations in females and adults aged ≥ 60 years, and geographic difference in the mortality risks and burdens.

Long-term exposure to wildfire smoke PM2.5 and mortality in the contiguous United States

“…Most previous studies have explored the relationship between wildfire and health outcomes by comparing periods with no fire and periods during or after fire events, or comparing regions affected by wildfire smoke and unaffected regions (22), which generated effect estimates that are difficult to directly compare to our estimates. Only a few studies have isolated wildfire- specific PM 2.5 from other sources, and used a continuous variable for smoke PM 2.5 concentrations instead of a binary variable to estimate the health effects of smoke PM 2.5 (9, 10). Our findings on the associations between smoke PM 2.5 and all-cause, cardiovascular, and respiratory mortality are consistent with these studies in terms of both magnitude and direction of the estimates.…”

“…In recent years, studies consistently reported a positive relationship between wildfire smoke exposure and all-cause mortality (7, 9, 10). Among specific causes of mortality, respiratory and cardiovascular diseases received most attention, with growing studies linking human exposure to wildfire smoke with increased risks of respiratory and cardiovascular mortality (9-11). However, in addition to the physical health harms, mental health can also be potentially threatened by wildfire smoke.…”

“…Furthermore, the effects of wildfire smoke PM 2.5 can be heterogenous among population subgroups due to physiological, behavioral, and socioeconomic factors (14). Previous studies indicated that demographic factors such as sex, age and race/ethnicity may modify the association between smoke PM 2.5 and health outcomes (9, 14, 15). However, existing research generated contradictory findings and is insufficient to identify specific subpopulations that are more susceptible to wildfire smoke exposure (7).…”

Health effects of wildfires

“…69 Despite strong established links between all-source PM and cardiovascular and cerebrovascular health, evidence related to wildfire smoke exposure has been mixed. 70 Some studies have reported positive associations between wildfire pollution and cardiovascular mortality 71 and morbidity, 67,72,73 including out of hospital heart attacks, 74,75 especially among older adults. 76 However, a number of studies have also reported non-meaningful association, non-statistically-significant differences, or even declines in cardiovascularrelated healthcare utilization (e.g., 54,[77][78][79][80] ).…”

Extreme Heat and Mental Health-Related Outcomes in Adolescent Populations: A Machine Learning Approach

“…for the temperature in the crossbasis function, df2= 2 for relative humidity, and df3= 7*number of years for the time trend to model for the season and long-term time trends. These parameters were identified based on previous studies[63][18][11][47][62] …”