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US particulate matter air quality improves except in wildfire-prone areas
Crystal D McClure1, Daniel A Jaffe2,3
1Department of Atmospheric Sciences, University of Washington, Seattle, WA 98195.
Summary
Fine particulate matter (PM2.5) levels are decreasing nationwide, except in the Northwest US. Wildfires are driving increasing PM2.5 in the Northwest, impacting air quality trends.
Area of Science:
- Environmental Science
- Atmospheric Science
- Public Health
Background:
- Air quality monitoring is crucial for understanding pollution trends.
- Fine particulate matter (PM2.5) poses significant health risks.
- Regional variations in PM2.5 trends require specific investigation.
Purpose of the Study:
- To evaluate trends in the 98th quantile of PM2.5 across the contiguous United States from 1988-2016.
- To investigate the influence of wildfire activity on PM2.5 trends in the Northwest US.
- To compare ground-based PM2.5 trends with satellite-derived aerosol optical depth (AOD) data.
Main Methods:
- Quantile Regression was used to calculate trends in the 98th quantile of PM2.5.
- Kriging and Gaussian Geostatistical Simulations were employed for spatial interpolation of trends.
- Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) data were analyzed for comparison.
Main Results:
- A positive trend in 98th quantile PM2.5 was observed in the Northwest US (0.21 ± 0.12 µg·m⁻³·y⁻¹).
- The rest of the US showed a negative trend in 98th quantile PM2.5 (-0.66 ± 0.10 µg·m⁻³·y⁻¹), attributed to emission reductions.
- Positive trends in total carbon and AOD in the Northwest supported wildfire activity as the cause for increased PM2.5.
Conclusions:
- PM2.5 levels are decreasing in most of the US, but increasing in the Northwest due to wildfires.
- Wildfire-driven PM2.5 trends in the Northwest are evident in both ground-based and satellite data.
- Continued monitoring is essential to understand and mitigate the impact of wildfires on regional air quality.
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