How long does coronavirus stay in the air after someone with COVID leaves the room?
August 8, 2022 - Coronavirus case levels in the Bay Area are still high as the highly infectious BA.5 variant makes its rounds, and local officials say they have no plans to reinstate mask mandates, which were lifted in California in February.
Generally, it’s true that once an infected person leaves the room, “the concentration of virus-laden aerosol particles in the room will decline,” said Richard Corsi, dean of UC Davis’ College of Engineering, who has extensive knowledge about indoor air quality.
The length of time the virus remains in the air depends on a number of factors, including the size of the droplet or aerosol carrying the virus, and the amount of clutter and air motion in the room, according to an aerosol protection FAQ by nearly a dozen experts from universities across the world, including Corsi.
The coronavirus has been found in tiny aerosols — even smaller than 1 micron — that can stay in the air for more than 12 hours. A 2021 study from Building and Environment, an international engineering journal, found that aerosols from speaking (not necessarily containing SARS-CoV-2) can stay in the air for up to nine hours.
The best way to protect yourself, experts say, is to social distance and wear high quality masks such as an N95, KN95 or KF94 mask while in indoor public spaces, in addition to being up to date on your COVID vaccinations.
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