Strategies for limiting airborne exposure is similar to strategies for staying dry when it’s raining. Just as the longer you stay in the rain, and the harder it’s raining, the wetter you will get, similarly, the more time you spend indoors with other people who are not from your household, the higher the exposure risk. Reducing risk is therefore based on decreasing both aerosol concentration levels and exposure time, and removing risk only comes from staying out of shared air environments completely.
An excellent source for information about protecting yourself and your family is the document “FAQs on Protecting Yourself from COVID-19 Aerosol Transmission.” Scientists and engineers with many years of collective research experience related to indoor air quality, aerosol science, aerosol disease transmission, and engineered control systems for aerosols, who are active researchers investigating aerosol transmission of COVID-19, created these FAQs and maintain them with updates.
There is no “safe distance” indoors, if ventilation and air quality is not addressed. Without ventilation, aerosols remain suspended in the air, becoming increasingly concentrated around people as time goes by. Speaking in a loud voice releases 50 times more virus-laden particles than when we don’t speak at all. These aerosols, if not diffused through ventilation, become increasingly concentrated, which increases the risk of infection.Aerosol concentrations can be reduced with increased ventilation, although recirculating the same air should be avoided unless the air can be effectively filtered prior to reuse. When possible, open doors and windows to increase fresh air flow.
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