A study conducted at the University of Southern California (USC), US, showed that exposure to air pollutants, in particular fine particles (PM2.5) and nitrogen dioxide (NO2), increased the risk of hospitalization in COVID-19 patients by up to 30%, including fully vaccinated individuals.

The study published in the American Journal of Respiratory and Critical Care Medicine revealed that over a long period, exposure to pollution led to cardiovascular and lung diseases, which were further associated with severe COVID-19 symptoms. On the other hand, for a short-term duration, air pollution worsened inflammation in the lungs and altered the immune response to the virus.

In the study, the researchers found that among 30,912 unvaccinated people, high short-term PM2.5 exposure increased the risk of COVID-19 hospitalizations by 13%, whereas long-term exposure increased the risk by 24%. Similarly, in the case of NO2 exposure, short-term exposure raised hospitalization risk by 14%. On the other hand, long-term exposure raised the risk by 22%. 

However, the researchers claimed that ozone exposure had no significant effect on COVID-19 hospitalizations. They also noted that for individuals who were partially or fully vaccinated, the risk of hospitalization related to air pollution exposure was slightly lower, although the difference was not statistically significant. 

(Source: https://health.economictimes.indiatimes.com/news/industry/air-pollution-may-increase-covid-severity-even-for-vaccinated-study/94536517 )