BOSTON - Health officials in Massachusetts have seen an unexpected trend when they look at Covid-19 infection hotspots.

That's because the six communities that have been hardest hit by the virus were all designated as environmental justice communities.

That means that all of them have high levels of air pollution as well as a high percentage of minority, low-income residents.

The six communities are Chelsea, Brockton, Everett, Lynn, Randolph, and Lawrence.

Each also reports a high number of people with asthma.

Researchers are beginning to see clear correlations between long-term exposure to air pollution and Covid mortality rates.

The Harvard study on pollution could help explain why the virus hits some cities harder than others.