Compared to people infected with the original form of the virus that causes COVID-19, those with a more recent strain exhaled 43 to 100 times more of it into the air, indicating that the disease is evolving to become more airborne, according to a new University of Maryland-led study.

The researchers also found that commonly used cloth and surgical masks reduce the amount of virus that gets into the air around infected people by about half. The study comparing the original form of SARS-CoV-2 to the Alpha variant—the dominant one when experimentation was conducted—was published last week in the journal Clinical Infectious Diseases.

“Our latest study provides further evidence of the importance of airborne transmission,” said Dr. Don Milton, professor of environmental health at UMD’s School of Public Health. “We know that the Delta variant circulating now is even more contagious than the Alpha variant.”

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