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. 2017 Jan;28(1):77-85.
doi: 10.1097/EDE.0000000000000556.

Wildfire-specific Fine Particulate Matter and Risk of Hospital Admissions in Urban and Rural Counties

Jia Coco Liu  1 , Ander Wilson, Loretta J Mickley, Francesca Dominici, Keita Ebisu, Yun Wang, Melissa P Sulprizio, Roger D Peng, Xu Yue, Ji-Young Son, G Brooke Anderson, Michelle L Bell
Affiliations

Wildfire-specific Fine Particulate Matter and Risk of Hospital Admissions in Urban and Rural Counties

Jia Coco Liu et al. Epidemiology. 2017 Jan.

Abstract

Background: The health impacts of wildfire smoke, including fine particles (PM2.5), are not well understood and may differ from those of PM2.5 from other sources due to differences in concentrations and chemical composition.

Methods: First, for the entire Western United States (561 counties) for 2004-2009, we estimated daily PM2.5 concentrations directly attributable to wildfires (wildfires-specific PM2.5), using a global chemical transport model. Second, we defined smoke wave as ≥2 consecutive days with daily wildfire-specific PM2.5 > 20 μg/m, with sensitivity analysis considering 23, 28, and 37 μg/m. Third, we estimated the risk of cardiovascular and respiratory hospital admissions associated with smoke waves for Medicare enrollees. We used a generalized linear mixed model to estimate the relative risk of hospital admissions on smoke wave days compared with matched comparison days without wildfire smoke.

Results: We estimated that about 46 million people of all ages were exposed to at least one smoke wave during 2004 to 2009 in the Western United States. Of these, 5 million are Medicare enrollees (≥65 years). We found a 7.2% (95% confidence interval: 0.25%, 15%) increase in risk of respiratory admissions during smoke wave days with high wildfire-specific PM2.5 (>37 μg/m) compared with matched non smoke wave days. We did not observe an association between smoke wave days with wildfire-specific PM2.5 ≤ 37 μg/mand respiratory or cardiovascular admissions. Respiratory effects of wildfire-specific PM2.5 may be stronger than that of PM2.5 from other sources.

Conclusion: Short-term exposure to wildfire-specific PM2.5was associated with risk of respiratory diseases in the elderly population in the Western United States during severe smoke days. See video abstract at, http://links.lww.com/EDE/B137.

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Conflict of interest statement

none to declare

Figures

Figure 1
Figure 1
Average number of Smoke Wave days/year for 561 Western US counties during 2004–2009. Hashed counties have population >75,000 in the 2010 Census.
Figure 2
Figure 2
Associations between hospital admissions and exposure to smoke-wave (SW) days (compared to non-smoke-wave days) for (a) cardiovascular disease and (b) respiratory disease, by different intensity (level of wildfire-specific PM2.5) definitions of a smoke wave.
Figure 3
Figure 3
Associations between hospital admissions and exposure to smoke-wave (SW) days (compared to non-smoke-wave days) for (a) cardiovascular disease and (b) respiratory disease, by timing of the days within a smoke wave.
See this image and copyright information in PMC

References

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    1. Interagency Working Group on Climate Change and Health . In: A Human Health Perspective on ClimateChange: A Report Outlining the Research Needs on the Human Health Effects of Climate Change. NIEHS EHPa, editor. 2010.

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