ALSO READ: Covid update: India sees rise in infections; active cases further decline "These findings are important because they show that, while COVID-19 vaccines are successful at reducing the risk of hospitalisation, people who are vaccinated and exposed to polluted air are still at increased risk for worse outcomes than vaccinated people not exposed to air pollution," senior research scientist at KPSC Anny Xiang said.
Published in the American Journal of Respiratory and Critical Care Medicine, the study estimated air pollution exposure levels for each participant based on their residential addresses.
The researchers looked at average PM2.5, NO2, and ozone (O3) levels during the one-month and one-year periods before each patient received a COVID-19 diagnosis. "We investigated both long-term and short-term air pollution exposure, which may influence COVID-19 severity through different mechanisms," assistant professor at USC, and co-first author of the study Zhanghua Chen said.
The researchers said over the long term, pollution is linked to increase in cardiovascular and lung diseases which are in turn associated with more severe COVID-19 symptoms.