Air Pollution Linked With More Severe COVID-19

The research showed that people exposed to more common air pollutants were at elevated risk of being admitted to the ICU.

A new study finds an association between air pollution and worse outcomes after COVID-19 infection

According to a recent study published in the Canadian Medical Association Journal, several common air pollutants, such as ground-level ozone, are related to more severe outcomes following SARS-CoV-2 infection, including admission to the intensive care unit (ICU).

To see whether there was a connection between long-term air pollution exposure and COVID-19 severity, researchers evaluated data on all 151,105 patients aged 20 and over with confirmed SARS-CoV-2 infection in 2020 in Ontario, Canada who were not in a long-term care facility. They created a simulation of historical exposure to three prevalent air pollutants before the pandemic: fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ground-level ozone (O3). The authors controlled for characteristics such as date of diagnosis, gender and age, being part of an outbreak, essential worker status, neighborhood socioeconomic status, health care access (including past influenza vaccine history, previous outpatient visits), and other factors.

“We observed that people with SARS-CoV-2 infection who lived in areas of Ontario with higher levels of common air pollutants (PM2.5, NO2, and O3) were at elevated risk of being admitted to the ICU after we adjusted for individual and contextual confounding factors, even when the air pollution level was relatively low,” writes Dr. Hong Chen, Health Canada and ICES, with coauthors.

They also found an elevated risk of hospitalization with chronic exposure to PM2.5 and O3, and an increased risk of death from COVID-19 with chronic exposure to O3.

These results add to the growing reports linking air pollution to COVID-19 severity from other countries, including Spain and Mexico.

“Given the ongoing pandemic, our findings that underscore the link between chronic exposure to air pollution and more severe COVID-19 could have important implications for public health and health systems,” write the authors.

As to the mechanisms of how long-term exposure to air pollution may be influencing the severity of COVID-19, the researchers call for more research.

The study was funded by Health Canada.

Reference: “Association between long-term exposure to ambient air pollution and COVID-19 severity: a prospective cohort study” by Chen Chen, John Wang, Jeff Kwong, JinHee Kim, Aaron van Donkelaar, Randall V. Martin, Perry Hystad, Yushan Su, Eric Lavigne, Megan Kirby-McGregor, Jay S. Kaufman, Tarik Benmarhnia and Hong Chen, 24 May 2022, Canadian Medical Association Journal.
DOI: 10.1503/cmaj.220068

Canadian Medical Association JournalCOVID-19ParticulatesPollution