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Your Covid-19 questions answered

Can Covid-19 carry in the wind?

10 June 2022 - 08:16
Experts say the coronavirus being transmitted via wind is unlikely.
Experts say the coronavirus being transmitted via wind is unlikely.
Image: Carlo Allegri

Officials in a Chinese city on the border with North Korea believe Covid-19 may be carrying in the wind over the border, and have instructed residents to close their windows, but experts say this is unlikely to be the case.

According to Bloomberg, Dandong has seen an increase in infections after North Korea revealed an outbreak in that country. Chinese health authorities said infections were occurring despite people not being outside their housing compounds for at least four days before being diagnosed.

A study from Turkey` in 2020 explored the relationship between population density and wind in Covid-19 infections and found “the virus is invisible in the air and spreads more in windy weather”.

However, Ben Cowling, chair of epidemiology at the University of Hong Kong’s School of Public Health, said it is unlikely because viruses don’t survive particularly well in sunlight and open air.

One study early in the pandemic found windy weather disperses viral particles and can reduce infection risk, while another found virus particles may only carry for 6m and become less concentrated the further they travel.

“When a person coughs, the wind speed in an open space environment significantly influences the distance that airborne disease carrier droplets travel. Without the surrounding wind speed, the droplets will fall to the ground a short distance from the person exhaling or coughing.

“The present analysis shows the range may not exceed 1m. A tiny number of particles may travel slightly further. However, their trajectory beyond 1m will already be at a height significantly below 0.5m dropping towards the ground. These droplets may not constitute a risk regarding facial contact of adults at this distance.

“At wind speeds from 4km/h to 15km/h, we found saliva droplets can travel distances up to 6m with a decrease in concentrations and liquid droplet size in the wind direction.”

The US Centres for Disease and Control and Prevention and SA’s National Institute for Communicable Diseases have noted the highest risk of transmission is within 1m to 2m and have urged social distancing.

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