Health Impact Assessment of the 2020 Washington State Wildfire Smoke Episode: Excess Health Burden Attributable to Increased PM_2.5 Exposures and Potential Exposure Reductions

Abstract

Major wildfires starting in the summer of 2020 along the west coast of the United States made PM 2.5 concentrations in this region rank among the highest in the world. Washington was impacted both by active wildfires in the state and aged wood smoke transported from fires in Oregon and California. This study aims to estimate the magnitude and disproportionate spatial impacts of increased PM 2.5 concentrations attributable to these wildfires on population health. Daily PM 2.5 concentrations for each county before and during the 2020 Washington wildfire episode (September 7–19) were obtained from regulatory air monitors. Utilizing previously established concentration‐response function (CRF) of PM 2.5 (CRF of total PM 2.5 ) and odds ratio (OR) of wildfire smoke days (OR of wildfire smoke days) for mortality, we estimated excess mortality attributable to the increased PM 2.5 concentrations in Washington. On average, daily PM 2.5 concentrations increased 97.1 μg/m 3 during the wildfire smoke episode. With CRF of total PM 2.5 , the 13‐day exposure to wildfire smoke was estimated to lead to 92.2 (95% CI: 0.0, 178.7) more all‐cause mortality cases; with OR of wildfire smoke days, 38.4 (95% CI: 0.0, 93.3) increased all‐cause mortality cases and 15.1 (95% CI: 0.0, 27.9) increased respiratory mortality cases were attributable to the wildfire smoke episode. The potential impact of avoiding elevated PM 2.5 exposures during wildfire events significantly reduced the mortality burden. Because wildfire smoke episodes are likely to impact the Pacific Northwest in future years, continued preparedness and mitigations to reduce exposures to wildfire smoke are necessary to avoid excess health burden.

Assessment of Smoke Pollution Caused by Wildfires in the Baikal Region (Russia)

“…Large areas of the BR are sparsely populated and do not have permanent air pollution monitoring posts. The lack of stationary observation posts in the vast territories makes it especially relevant to search for opportunities to assess atmospheric air pollution and its danger for the population of small settlements, remote from large centers, with a developed infrastructure for monitoring the quality of the environment and providing emergency medical care in emergency situations [37]. Krstic and Henderson, after analyzing data on smoke and clouds from the Canadian Terra-MODIS 2000-2007, suggested that the average daily measurements of the optical thickness of aerosols can be used to represent the smoke levels in the area and make urgent decisions about the evacuation of the population [11].…”

Ten new insights in climate science 2021: a horizon scan

“…Smoke from wildfires also affects local and distant air quality (the 2019-2020 Australian wildfires affected New Zealand and South America) (Nguyen et al, 2021), and smoke from Siberian fires has affected North America . The full health impact of the 2019-2020 wildfires will not be known for some time due to lags in the availability of health data, but current assessments estimate around 90 increased deaths in Washington State (Liu et al, 2021) in 2020, and over 400 additional deaths and a few thousand increased hospitalizations from the 2019-2020 bushfires in Australia (Borchers Arriagada et al, 2020). Because these studies rely on concentration-response functions from non-wildfire air pollution studies, we would expect the number of deaths related to wildfire smoke to rise when using a potentially steeper concentration-response function for wildfire smoke (Aguilera et al, 2021;Kiser et al, 2020).…”

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“…It is determined by debugging in the simulation process. The third step was logistic regression analysis (Liu & Austin, 2021). Logistic stepwise regression was used to analyze the relationship between spatial distribution and driving factors of land use types.…”