Ambient air pollution and COVID-19 in California

This study will investigate the chronic and acute effects of air pollution exposure on COVID-19 incidence, mortality, and long-term complications, including onset of disease formation. Long- (2017−2018) and short- (2020) term exposures will be linked to a large medical records database in Southern California, with assessments at both the neighborhood and individual level.

Poster abstract for HEI Annual Conference 2023

Air Pollution and COVID-19 severity among hospitalized COVID-19 Patients: A Multistate Survival Analysis

Michael Jerrett¹, Michael Kleeman², Jason Su³, Claudia Nau⁴, Deborah Young⁴, Rebecca Butler⁴, Christina Batteate¹, Ariadna Padilla⁴, Sara Y. Tartof⁴, Richard Burnett

¹University of California at Los Angeles, Los Angeles, CA, USA; ²University of California at Davis, Davis, CA, USA; ³University of California at Berkeley, Berkeley, USA; ⁴Kaiser Permanente Southern California, Los Angeles, CA, USA

Background: Efforts to limit the severity of COVID-19 outcomes have faced challenges due in part to vaccine hesitancy and low uptake of boosters. Growing interest centers on modifiable environmental risk factors such as air pollution that may limit the severity of COVID-19 in infected patients. Some evidence implicates air pollution as a risk factor for more severe outcomes in COVID-19 patients. To date, however, no studies have examined comprehensively how air pollution affects the severity of COVID-19 outcomes as measured by admission to the intensive care units, death and time to hospital discharge.

Methods: A multistate survival model was developed in a cohort of 15,978 hospitalized patients with COVID-19 who were members of Kaiser Permanente Southern California (KPSC), a large, integrated health care system with membership that is highly diverse.  KPSC documents all care in its electronic health records.  The multistate model captured all possible states of transition between standard hospital care, intensive care and discharged from the hospital to quantify the association of air pollution exposure on the transition between states in patients with COVID-19: hospitalization, admission to ICU, recovery and discharge, or death (in or out of hospital Chronic air pollution exposure fields were developed across Southern California using chemical transport models (CTMs) and Land Use Regression Models (LURMs) with a spatial resolution of 1 km.  Results were analyzed for PM_2.5 mass, O₃, and NO₂ in single pollutant models and two pollutant models for all possible combinations.

Results: Increased exposure to PM_2.5 mass and O₃ was associated with the transition to more severe COVID states, including: ICU admission after hospitalization, death after hospitalization, and death after recovery or discharge from hospital. Effects for NO₂ were somewhat weaker than for PM_2.5 mass and O₃. Lower air pollution concentrations were associated with recovery after hospitalization.

Conclusions: Given the public health challenges of mitigating COVID-19 and potential new  viruses, other approaches to limiting the severity of COVID-19 infection are essential.  Reducing air pollution may provide another effective means of reducing the severity of the current pandemic, while also by limiting the impact of  future novel viruses.