face coverings

Early in the pandemic, droplets from coughs and contaminated surfaces were seen as the main routes of transmission – which is why social distancing and hand washing were highlighted as vital measures. China denied for a long time (as did the WHO!) that the virus was being passed airborne, by breathing in the exhalations of infected people.

But the possibility of a third route - what’s called "aerosol transmission" – in which infectious virus particles linger in the air, was only recently acknowledged by the World Health Organization.  

Airborne virus particles probably play a role in "superspreading events" where the infection is passed to large numbers of people in poorly ventilated spaces such as churches and restaurants.

And while outdoors the virus can be scattered by the breeze, and weakened by sunlight, indoors it can survive in the air for up to five or more hours.

One recommendation is for people to wear masks to reduce how much virus they might release, and to reduce how much virus they breathe in. The less virus released the better, and the less breathed in, the better. Illness is less severe with lower rates of virus intake.  Wear a mask indoors and outdoors in crowds and even medium level population densities. 

Whether or not to wear a face covering is an important decision when Covid-19 is active in your area. Better safe than sorry is a good guide here. Many countries and states and cities are requiring them in some situations. 

To understand why face masks might work, it is important to look at how the virus that causes Covid-19 spreads in the first place.

Once it has infected someone, the Sars-CoV-2 virus responsible for the disease hijacks their cells to replicate itself. As it multiplies, these new virus particles then burst out of the cells and become suspended in the bodily fluids in our lungs, mouth and nose. When an infected person coughs, they can send showers of tiny droplets – known as aerosols – filled with the virus into the air.

A single cough can produce up to 3,000 droplets. There are fears the virus can also be spread simply through speaking. One recent study showed that we spray thousands of droplets invisible to the naked eye into the air just by uttering the words “stay healthy”.