Dust storms and emergency department visits in four southwestern US states

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ABSTRACT Dust storms are atmospheric events precipitated by strong winds that cause dust on the ground to be suspended, severely reducing air quality and visibility. Dust storm air pollution is largely characterized by high concentrations of particulate matter from soil that can contain heavy metals, pesticides, and spores or conidia of microorganisms. Studies in East Asia, southern Europe, and Australia have demonstrated short-term adverse cardiorespiratory health effects of dust storms. In the United States, dust storm activity has increased over the past 20 years, particularly in the southwestern region due to its arid climate. However, despite high dust activity in many states, the US has lagged behind in the study of dust storms and their health effects. This 2-year project will fill this important knowledge gap by utilizing (1) new approaches to characterize dust storms retrospectively, and (2) an existing database of patient-level emergency department (ED) visits and hospitalizations. In this project, we will characterize dust storms exposures using a number of different approaches and data sources. This is motivated by the well-recognized exposure assessment challenge in dust storm research due to the sparse number of monitors for ambient coarse particulate matter and the lack of standardized classifications for dust storms. In Aim 1, we will compile several dust storm exposure metrics, including (1) two monitor-based dust event metrics from regulatory ambient air pollution monitoring networks, (2) a data product combining atmospheric model simulation and satellite-derived aerosol optical depth, (3) a ground-based aerosol optical depth inversion product, and (4) reports in the United States National Weather Service Storm Database. We will then examine the spatial-temporal concordance of different dust storm metrics, as well as consistency between their long-term dust event frequency trends and seasonal profiles. In Aim 2, we will assess associations between dust storm events and daily ED visits in four southwest US states during the period 2005 to 2016. Specifically, we will conduct time-series analyses to estimate short-term associations between dust storm events and ED visits Arizona, California, Nevada, and Utah for various outcomes, including allergic reactions, cardiorespiratory diseases, infections, and those caused by motor vehicle accidents. One particular outcome of interest is valley fever because the study region includes endemic areas for valley fever. Increased spore transmission via windblown dust has been suggested to contribute to the recent rise in valley fever incidence. Robustness of risk estimates using different dust storm exposure metrics and exposure lag structures will be evaluated. Results from this project will contribute to our knowledge in the health effects of dust storms in the United States, provide directions to improve exposure assessment for windblown dust and dust storm events, and provide support for subsequent studies to examine effect modification by individual-level and community-level factors, as well as by dust storm characteristics that may confer vulnerability.