Critical Review of Health Impacts of Wildfire Smoke Exposure

Abstract

Background:Wildfire activity is predicted to increase in many parts of the world due to changes in temperature and precipitation patterns from global climate change. Wildfire smoke contains numerous hazardous air pollutants and many studies have documented population health effects from this exposure.Objectives:We aimed to assess the evidence of health effects from exposure to wildfire smoke and to identify susceptible populations.Methods:We reviewed the scientific literature for studies of wildfire smoke exposure on mortality and on respiratory, cardiovascular, mental, and perinatal health. Within those reviewed papers deemed to have minimal risk of bias, we assessed the coherence and consistency of findings.Discussion:Consistent evidence documents associations between wildfire smoke exposure and general respiratory health effects, specifically exacerbations of asthma and chronic obstructive pulmonary disease. Growing evidence suggests associations with increased risk of respiratory infections and all-cause mortality. Evidence for cardiovascular effects is mixed, but a few recent studies have reported associations for specific cardiovascular end points. Insufficient research exists to identify specific population subgroups that are more susceptible to wildfire smoke exposure.Conclusions:Consistent evidence from a large number of studies indicates that wildfire smoke exposure is associated with respiratory morbidity with growing evidence supporting an association with all-cause mortality. More research is needed to clarify which causes of mortality may be associated with wildfire smoke, whether cardiovascular outcomes are associated with wildfire smoke, and if certain populations are more susceptible.Citation:Reid CE, Brauer M, Johnston FH, Jerrett M, Balmes JR, Elliott CT. 2016. Critical review of health impacts of wildfire smoke exposure. Environ Health Perspect 124:1334–1343; http://dx.doi.org/10.1289/ehp.1409277

Cardiovascular and Cerebrovascular Emergency Department Visits Associated With Wildfire Smoke Exposure in California in 2015

“…One recent review found that most studies with combined cardiovascular outcomes have found no significant associations, although some specific outcomes have been shown to be increased in the context of wildfire smoke, such as out‐of‐hospital cardiac arrest, heart failure, and ischemic heart disease 11. Another review found that 6 of 14 studies revealed statistically significant associations of wildfires and cardiovascular outcomes 12.…”

“…While the aim of this study was to explore cardiovascular and cerebrovascular health impacts attributable to wildfire smoke, respiratory outcomes were included for external validity, given the strong associations between wildfire‐PM 2.5 and respiratory disease that have been documented elsewhere, including asthma, COPD, and some respiratory infections such as pneumonia 11, 12. As with other studies, positive associations were found between wildfire smoke and asthma, COPD, pneumonia, and respiratory‐related chest pain symptoms.…”

“…Fine particulate matter (<2.5 μm in diameter [PM 2.5 ]) is a known respiratory irritant and causally related to cardiovascular morbidity 11, 12, 13. PM 2.5 passes deep into the lung and has been shown to increase systemic inflammation, oxidative stress, and coagulation through PM 2.5 ‐mediated changes in the autonomic nervous system 11, 14.…”

“…Fine particulate matter (<2.5 μm in diameter [PM 2.5 ]) is a known respiratory irritant and causally related to cardiovascular morbidity 11, 12, 13. PM 2.5 passes deep into the lung and has been shown to increase systemic inflammation, oxidative stress, and coagulation through PM 2.5 ‐mediated changes in the autonomic nervous system 11, 14. This has been linked to cardiovascular health impacts such as ischemic heart disease and cerebrovascular events such as ischemic stroke in the ambient air pollutant PM 2.5 literature 11, 15, 16, 17, 18.…”

“…PM 2.5 passes deep into the lung and has been shown to increase systemic inflammation, oxidative stress, and coagulation through PM 2.5 ‐mediated changes in the autonomic nervous system 11, 14. This has been linked to cardiovascular health impacts such as ischemic heart disease and cerebrovascular events such as ischemic stroke in the ambient air pollutant PM 2.5 literature 11, 15, 16, 17, 18. Other air pollutants in wildfire smoke have also been linked to cardiovascular and respiratory outcomes in urban and ambient air pollution studies, including nitrogen oxides, carbon monoxide, and ozone 7, 8, 9, 10…”