Association between exposure to airborne pollutants and COVID-19 in Los Angeles, United States with ensemble-based dynamic emission model

https://doi.org/10.1016/j.envres.2020.110704Get rights and content

Highlights

  • Machine learning & network science are used to study air pollution's impact on COVID.

  • EDEM: a specialized method for emission modeling is proposed.

  • Analysis of exposure to PM2.5 and PM10 shows a negative link with COVID-19 cases.

  • Short-term exposure to O3 with a lag of 7 days is positively linked with the cases.

  • Automobiles are the major source of O3 and its precursors.

Abstract

This study aims to find the association between short-term exposure to air pollutants, such as particulate matters and ground-level ozone, and SARS-CoV-2 confirmed cases. Generalized linear models (GLM), a typical choice for ecological modeling, have well-established limitations. These limitations include apriori assumptions, inability to handle multicollinearity, and considering differential effects as the fixed effect. We propose an Ensemble-based Dynamic Emission Model (EDEM) to address these limitations. EDEM is developed at the intersection of network science and ensemble learning, i.e., a specialized approach of machine learning. Generalized Additive Model (GAM), i.e., a variant of GLM, and EDEM are tested in Los Angeles and Ventura counties of California, which is one of the biggest SARS-CoV-2 clusters in the US. GAM depicts that a 1 μg/m3, 1 μg/m3, and 1 ppm increase (lag 0–7) in PM 2.5, PM 10, and O3 is associated with 4.51% (CI: 7.01 to −2.00) decrease, 1.62% (CI: 2.23 to −1.022) decrease, and 4.66% (CI: 0.85 to 8.47) increase in daily SARS-CoV-2 cases, respectively. Subsequent increment in lag resulted in the negative association between pollutants and SARS-CoV-2 cases. EDEM results in an R2 score of 90.96% and 79.16% on training and testing datasets, respectively. EDEM confirmed the negative association between particulates and SARS-CoV-2 cases; whereas, the O3 depicts a positive association; however, the positive association observed through GAM is not statistically significant. In addition, the county-level analysis of pollutant concentration interactions suggests that increased emissions from other counties positively affect SARS-CoV-2 cases in adjoining counties as well. The results reiterate the significance of uniformly adhering to air pollution mitigation strategies, especially related to ground-level ozone.

Keywords

Air pollution
COVID-19
California
Ensemble learning
Machine learning
Network science
Centrality measures

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