Source-specific acute cardio-respiratory effects of ambient coarse particulate matter exposure in California’s Salton Sea region

Abstract Windblown dust is an ongoing air quality and public health concern among residents living around California’s Salton Sea, a region characterized by critical socioeconomic and health outcome disparities. Dropping water levels and unique biogeochemistry at the Salton Sea have raised concerns regarding the human health impacts of drying sediments exposed on shrinking shorelines, as well as potential lake spray emissions from the water surface itself. As particles emitted from different surface types can differ greatly in terms of composition, size distribution, and other properties, variability in the resulting health impacts of windblown particulates reaching communities in the region may likewise be source dependent. However, these potential effects remain understudied. Here we use observed coarse particulate matter (PM c ) concentrations and modeled atmospheric back trajectories along with land surface data to estimate individual source region contributions to particulates observed at long term surface air quality monitoring sites in the Salton Sea region. We then apply these data products to an analysis of source-specific acute cardio-respiratory impacts using a time-stratified case crossover design with conditional logistic regression based on 171 465 hospitalizations cases recorded from 2008 to 2019. To assess source-specific health impacts, we quantify and compare the acute health effects of dust arriving from different directions and from over different source surfaces on daily respiratory and cardiovascular hospitalizations. Using a remote sensing chlorophyll-a data product, we further investigate the possible influence of periodic bloom events—a result of ongoing nutrient loading into the Salton Sea—on those hospitalizations. Results suggest that a 10 μ g m −3 increase in coarse PM coming from over the Salton Sea is associated with an 8.6% (Risk Ratio, RR = 1.086, 95% CI: 1.028–1.147) increased risk of respiratory hospital admissions; increases that are greater than those for dust likely originating from other surface types. Furthermore, we find even higher RR values for dust associated with Salton Sea back trajectories during bloom events: a 24.9% (RR = 1.249 95% CI: 1.031–1.514) increased risk in respiratory hospitalization. Our findings suggest that exposure to dust and aerosols potentially originating from the Salton Sea or surrounding surfaces is associated with increased respiratory hospitalizations, especially during observed bloom events. Further research is needed to determine the underlying mechanisms responsible for these health impacts, as well as possible primary or secondary preventive strategies.