#Air-conditioned rooms help spread COVID-19, research shows

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A new study says relative humidity plays an important role in the spread of coronavirus.
Tilo Arnhold/TROPOS

Dry air and air-conditioned rooms can help spread the coronavirus, according to an Indian-German research team that looked at the role of relative humidity in the transmission of infections.

For office workers and students worldwide, the findings are important as they head back to their desks after months in lockdown.

“The role of humidity seems to be extremely important to the airborne spread of COVID-19 in indoor environments,” the researchers reported. on the website of Germany’s Leibniz Institute for Tropospheric Research (TROPOS).

The scientists, who reviewed 10 international studies of swine flu and other infectious diseases such as Middle East Respiratory Syndrome, found humidity affects a virus in three ways: droplet size, how droplets float and how droplets land on surfaces.

In more humid rooms, virus droplets become heavier and fall faster in higher humidity, “providing less chances for other people to breathe in infectious viral droplets,” the team wrote, according to DW, a German news website.

Dry air makes the droplets shrink and hang around, becoming what the scientists describe as an “optimal route” for transmission.

Low humidity also dries out mucous membranes in the nose, making an easier way in for the coronavirus, they wrote.

Rooms should have a relative humidity of 40% to 60% — open the windows, the researchers urge — to keep a virus from spreading and governments should include the recommendation in any public health guidelines, the team found.

Besides raising the relative humidity and wearing face masks, the scientists are urging businesses and schools to not pack their rooms with people.