The World Health Organization (WHO) and other health experts have confirmed the airborne transmission of the coronavirus. Apart from droplets, COVID-19 spreads via aerosols. Here are the differences and how the virus spreads:
Droplets
When you cough or sneeze, a spray of mucus and saliva droplets fly out of your mouth and nose. These droplets measure between 5 and 10 micrometers in diameter, and contain particles of the virus if the person is infected. These droplets are pulled down by gravity as soon as they are ejected, and fall on the ground by the time one leaves the room. Hence, a 6-feet social distance is safe to prevent infection.
Aerosols
This is where the main problem comes. Some of the smaller droplets evaporate faster than they fall to the ground. The virus particles from these evaporated droplets remain suspended and float in the air for up to half an hour or longer according to some studies. Hence it is possible to contract the virus by entering an empty room in which an infected person was present several minutes earlier. Also, these aerosols are emitted in thousands when breathing and talking.
This transmission via free-drifting aerosols is why WHO has defined COVID-19 as an airborne disease.
In July, the WHO had cited 3 cases of infections in a gym, choir practice and a restaurant. It said, “Short-range aerosol transmission, particularly in specific indoor locations, such as crowded and inadequately ventilated spaces over a prolonged period of time with infected persons, cannot be ruled out.”
Aerosols make it particularly dangerous in closed places where air is recirculated. The WHO recommends increasing fresh air intake in air conditioners and to allow ventilation by opening windows wherever possible. Experts also recommend using HEPA filters to trap the virus.
Wearing an N95 respirator is one of the best ways to prevent airborne infection. Cloth and surgical masks are effective only against droplets, not aerosols.
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