What’s the risk of transmission if I’m sharing indoor space with an infected person? What can I do to reduce my risk?

Infection and Spread

A: Because the virus can travel in small aerosols that accumulate indoors, transmission risk is strongly related to crowded, poorly ventilated rooms with loud talking and no masks for long durations of time.

This means you can greatly reduce your risk by following the Nerdy Girls #StaySMART principles:

SPACE – Keep your distance (more than 6 feet is great)

MASK – Wear a mask

AIR – Ensure good ventilation—open windows/doors if possible

RESTRICT – Limit the number of people

TIME – Limit the duration

We highly recommend this article with AMAZING visualizations that simulate aerosol transmission scenarios in a private home, bar and school.

The simulations are based on studies of aerosol transmission and information from real outbreaks such as the choir rehearsal in Washington State. They assume that patient zero is very infectious, but in reality, it’s still unclear exactly how much virus an average infected person sheds.

Rather than *precise* infection probabilities, these numbers should be taken as reflecting the ballpark magnitude of effects and relative strengths of different types of prevention actions.

Key take-aways:

• Loud talking and shouting/singing increase risk dramatically, as a loud voice releases 50 times more virus-laden particles than not speaking at all.


In these simulations all subjects were more than the recommended safe distance eliminating droplet transmission, but the other preventive measures of ventilation, shortening the encounters, reducing the number of participants and wearing face masks were still needed to prevent transmission.

• In all scenarios, wearing masks reduces infection risk somewhat, while high levels of ventilation and reducing duration make a big difference in how many people are infected.

Stay Safe and Stay Sane!

Those Nerdy Girls

Link to coverage of simulations with caveats

Previous DP posts on aerosol transmission:

Will the 6 feet/2 meter rule keep me safe indoors?

I still have *so* many questions about aerosol transmission.

What’s the most likely way to catch SARS-CoV-2? Do I still need to Lysol the bejeesus out of everything?

Link to original FB post