Ambient air-pollution and COVID-19

Abstract

Background and Aims. The COVID-19 pandemic is challenging the world’s economic and health systems, and introduced completely new challenges. The outbreak of COVID-19 highlighted the links between the occurrence of new infections, the environment and climate at a global scale and the need for trans-disciplinary approaches. Emerging evidence links ambient air pollution with COVID-19 disease, an association that is methodologically challenging to investigate. Methods. I will review the evidence on ambient air pollution Covid -19 disease and disease severity and discuss potential biases. I will further discuss new research areas on the association of air-pollution with post-COVID-19 condition (long-COVID) and with immune response associated with natural infection and with vaccine response. Results. More than 100 studies have been published globally on air-pollution and Covid-19 reporting more than 400 separate pollutant-COVID-19 effect estimates. Most studies to date have employed ecological designs, associating group-level air pollution exposures with aggregate COVID-19 outcomes over a broad geographic domain. Many of these studies relied on COVID-19 disease incidence estimated from surveillance data. Differences in the associations between long-term and short term exposures to air pollution and COVID-19 incidence and severity have been poorly evaluated. Studies using individual-level designs, which can avoid the potential for clustering of cases and that did extensive adjustment for potential confounders including contextual variables, convincingly show that exposure to air pollution is associated with COVID-19 disease and mortality. The few existing studies evaluating immune response show an association of air-pollution with higher levels of antibody response among infected and also depressed immune response among non-infected vaccinated. There is still scarce evidence on air pollution and long-COVID. Conclusions. The pandemic has highlighted the deep interconnections between the environment and infectious diseases and specifically the association of air pollution with COVID-19 through multiple biological pathways. Keywords: COVID-19; air pollution; long-COVID; immune response