Evidence is emerging that environmental exposures—including air pollution, chemical exposures, climate, and the built environment—modify COVID-19 risk, yet our understanding of these effects is hindered by limited mechanistic, epidemiologic and causal findings. We reviewed the mechanistic and epidemiologic literature to characterize the strength of evidence regarding associations between environmental exposures and COVID-19 susceptibility and severity. These exposures can be grouped into a series of interlocking mechanisms including increased risk of pre-existing conditions associated with disease severity, immune system impairment, viral survival and dispersion, behavioral change, and increased risk of viral exposure. Studies have found varying degrees of positive association between air pollution and COVID-19 incidence and mortality, yet ecological design and limited exposure and outcome data prevent casual interpretation and introduce significant biases. Air pollution is thought to affect COVID-19 through increased comorbidities, direct damage to the immune system, and physical facilitation of viral spread. Current evidence supports immune impairment and comorbidity risk as dominant pathways. Chemical exposures—including EDCs, PFAS, and metals—are under-studied, but are hypothesized to contribute to immune system impairment and increase the risk of comorbidities associated with poor COVID-19 outcomes. Causal inference of the role of chemical exposures on COVID-19 incidence and severity will require studies capable of addressing exposures to complex mixtures and heterogeneity in lifecourse exposures. While meteorological conditions—including temperature, humidity, and UV radiation—are well-established drivers of seasonality in related viral respiratory infections, evidence is conflicting as to the strength and direction of their relationships with COVID-19 incidence. The built environment is known to affect COVID-19 susceptibility and risk through modifying indoor conditions, limiting social distancing, and codifying structural inequalities historically detrimental to community health. Research is evolving quickly, even as the field contends with several major methodologic issues. We conclude by reviewing areas contributing significant uncertainty to our understanding of COVID-19 environmental relationships and evidence for environmental actions that might simultaneously address the COVID-19 pandemic and environmental determinants of health.

Environmental exposures and their impacts on SARS-CoV-2 transmission and COVID-19 susceptibility and severity

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.