Sign up

Global Science TV: The facts about airborne transmission

Watch and share the latest Global Science TV episode on preventing airborne transmission of the SARS-CoV-2. ISC members are invited to embed this video on...

Watch and share the latest Global Science TV episode on preventing airborne transmission of the SARS-CoV-2. ISC members are invited to embed this video on your own Youtube channels or websites in local languages.


Hi, Nuala Hafner here from Global Science, answering more of your questions about the coronavirus.

And this is a biggie: is the virus that causes COVID-19 airborne?

Well, in the right circumstances, it can be. But first, let’s get some definitions sorted.

We need to know the difference between large respiratory droplets and aerosols.

The larger of the two are usually forced to the ground by gravity within about 1.5 metres from the source person.

They might come out when we’re talking to someone. Hence that repeated messaging about physical distancing.

Aerosols are smaller particles that rapidly evaporate, but they leave behind droplet nuclei, less than five microns in diameter, really tiny, containing less virus than the larger droplets, but they’re so small and light that they can remain suspended in the air for hours. And that’s what we’re talking about here.

Are those floating aerosols helping to spread Covid-19?

Well, some medical procedures have the ability to produce aerosols, that’s why it’s vital for health workers to wear personal protective equipment, especially, of course, if they’re treating someone with Covid-19.

It stops them from inhaling those particles. But what about elsewhere?

After all, we know there have been outbreaks of COVID-19 in confined places such as restaurants and nightclubs.

Marylouise McLaws: “It likes indoors and it likes people to talk, and if they talk louder, if they sing, if they shout, you’re pushing more particles out and potentially keeping them in the air for the next person to breathe in.”

A lot of that is person-to-person transmission through those large droplets I mentioned.

Remember, keep your distance, wear a mask in high-risk or crowded areas, and keep washing your hands.

But what about aerosols?

You may have seen that 239 scientists from 32 countries penned an open letter to the World Health Organization, urging it to strengthen its advice around airborne transmission of SARS- COV-2, or what’s better known as Covid-19.

The WHO now says:

“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.”

Marylouise McLaws: “Scientists and epidemiologists have actually done air sampling, and in one study they found no SARS-CoV-2. In another group they found a very, very low level, but that does not mean it’s at a high enough level to cause infection.”

More studies are underway into the significance of airborne transmission. In the meantime, the best advice is to ensure good ventilation.

Open windows and doors, or if you’re using air-con, don’t use the recirculate setting, and don’t sit under the direct air flow, because that air flow can push those floating aerosols along.

So, better yet, head outside, while maintaining physical distancing, or wear a mask if you can’t.

And even if you’re wearing a mask, now is not the time to be relaxing about washing your hands.

Keep clean and keep safe.

Skip to content