The worse the local air contamination, the higher the odds of needing intensive care and mechanical ventilation.

Anita Shallal of Detroit's Henry Ford Hospital said long-term exposure to air pollution may impair the immune system and make it more susceptible to viral infections, while fine particles in air pollution may also act as a carrier for the virus and help it spread.

The study "calls attention to the systemic inequalities that may have led to the stark differences in Covid-19 outcomes along racial and ethnic lines," Shallal said in a statement from the European Congress of Clinical Microbiology and Infectious Diseases, where she presented the findings on Friday.

"Communities of colour are more likely to be located in areas closer to industrial pollution, and to work in businesses that expose them to air pollution," she said.

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