Spatial Particulate Fields during High Winds in the Imperial Valley, California

Frank R Freedman,Akula Venkatram,Paul English,Ana Rivera,Meytar Sorek-Hamer,Mohammad Z Al-Hamdan,Patrick L Kinney,Yang Liu,Daniel Q Tong,Robert Chatfield,Jeff Wagner

doi:10.3390/atmos11010088

Abstract

We examined windblown dust within the Imperial Valley (CA) during strong springtime west-southwesterly (WSW) wind events. Analysis of routine agency meteorological and ambient particulate matter (PM) measurements identified 165 high WSW wind events between March and June 2013 to 2019. The PM concentrations over these days are higher at northern valley monitoring sites, with daily PM mass concentration of particles less than 10 micrometers aerodynamic diameter (PM10) at these sites commonly greater than 100 μg/m3 and reaching around 400 μg/m3, and daily PM mass concentration of particles less than 2.5 micrometers aerodynamic diameter (PM2.5) commonly greater than 20 μg/m3 and reaching around 60 μg/m3. A detailed analysis utilizing 1 km resolution multi-angle implementation of atmospheric correction (MAIAC) aerosol optical depth (AOD), Identifying Violations Affecting Neighborhoods (IVAN) low-cost PM2.5 measurements and 500 m resolution sediment supply fields alongside routine ground PM observations identified an area of high AOD/PM during WSW events spanning the northwestern valley encompassing the Brawley/Westmorland through the Niland area. This area shows up most clearly once the average PM10 at northern valley routine sites during WSW events exceeds 100 μg/m3. The area is consistent with high soil sediment supply in the northwestern valley and upwind desert, suggesting local sources are primarily responsible. On the basis of this study, MAIAC AOD appears able to identify localized high PM areas during windblown dust events provided the PM levels are high enough. The use of the IVAN data in this study illustrates how a citizen science effort to collect more spatially refined air quality concentration data can help pinpoint episodic pollution patterns and possible sources important for PM exposure and adverse health effects.

Highlights

The Imperial Valley, which is an agriculturally dominated area located in Southeastern California adjacent to the US-Mexico border, has among the highest particulate matter (PM) air pollution concentrations in the United States
We examined windblown dust within the Imperial Valley (CA) during events that occurred in spring due to strong west-southwesterly (WSW) winds, which are the most common type affecting the valley
Routine site ambient daily-averaged PM10 and PM2.5 concentrations are clearly higher at northern (Westmorland, Brawley, and Niland) as compared with the southern (El Centro and Calexico) valley sites, with PM10 concentrations at the northern sites routinely greater than 100 μg/m3 and reaching as high as around 400 μg/m3 for the days analyzed

Summary

Introduction

The Imperial Valley, which is an agriculturally dominated area located in Southeastern California adjacent to the US-Mexico border, has among the highest particulate matter (PM) air pollution concentrations in the United States. The PM2.5 fraction yields the strongest correlations with respiratory and cardiovascular health effects due to the ability of these fine particles to penetrate deep into the lungs [4]. Larger PM10 particles deposit in the nose and upper airways and are associated with increased inflammation, asthma, and respiratory effects [5,6]. Windblown dust, which is a important component of coarse PM10, has been associated with a variety of adverse health effects, including cardiovascular mortality [7], heart attacks [8], and Coccidioidomycosis, commonly known as Valley Fever, an infection caused by inhalation of a soil-dwelling fungus. Valley Fever has increased in incidence by 800% from 1998 to 2011 across the United States, with much of this increase in the southwestern U.S, where windblown dust is common [9,10]

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