Statement on the state of the science linking long-term air pollution exposure with SARS-CoV-2 infection and adverse COVID-19 outcomes

Committee on the Medical Effects of Air Pollutants

Research output: Book/ReportOther report

Abstract / Description of output

Since the start of the pandemic in 2020, a large amount of research has been published linking air pollution and COVID-19 but these studies have varied in quality and content. Previous research has established that long-term exposure to air pollution contributes to the development and worsening of conditions such as cardiovascular and respiratory disease. These conditions have been shown to increase the risk of severe COVID-19 disease compared to healthy individuals. Previous research has also found that exposure to outdoor and indoor air pollutants can put people at risk of other respiratory infections and worsen outcomes. Hence, it has been proposed that air pollution may contribute to SARS-CoV-2 infection and COVID-19 severity.
This statement evaluates the current ‘state of the science’ on the association between air pollution and COVID-19. It focuses on individual-level studies linking long-term exposure to air pollution with SARS-CoV-2 infection and COVID-19 outcomes in human populations (epidemiological studies), and on studies of how air pollution might affect the body’s response to the virus (mechanistic studies).
We conclude that, in the context of evidence for the effect of air pollution on lung infections more generally, long-term air pollution may be a contributory factor in worsening the symptoms of COVID-19. Currently, there are a limited number of good quality studies on COVID-19 and these studies are often inconsistent in their findings. Based on evidence reviewed, published up to the end August 2022, there is not enough epidemiological evidence to suggest that long-term exposure to air pollution increases the risk of infection with the SARS-CoV-2 virus that causes COVID-19 disease. There is more evidence that long-term exposure to PM2.5 air pollution can increase the severity of COVID-19 disease once someone is infected with SARS-CoV-2, with an increased risk of hospitalisation following infection. The evidence for an increased risk of death from COVID-19 is less clear, with few studies available. A small number of studies are available relating to possible mechanisms and these suggest ways air pollution can alter the body’s immune function and, consequently, increase risk of infection with the SARS-CoV-2 virus and disease severity. We did not find convincing evidence to support air pollution particles having an important role in transporting viable SARS-CoV-2 virus in the environment.
We acknowledge that studies linking air pollution and COVID-19 are difficult to conduct and hard to interpret. Studies need careful control for other factors that may influence exposure to the virus and severity of disease. Higher concentrations of air pollution are more likely to occur in more deprived areas containing individuals at higher risk of infection and severe disease. In addition, measures implemented to prevent the spread of the disease (for example ‘lockdown’, additional time working from home, wearing of facemasks) will affect both health outcomes and levels of air pollution.
We do not consider it appropriate to attempt to quantify the effects of air pollution on COVID-19 outcomes at present, but this may change as more evidence becomes available. More research is required, particularly to help understand the influence that air pollution may have on susceptibility to, and recovery from COVID-19, immune function and the body’s response to vaccination.
Original languageEnglish
PublisherUK Health Security Agency
Number of pages45
Publication statusPublished - 6 Sept 2023

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