How fast does air leave a room? It is complicated. Think about a cup of black coffee. How much milk do we have to add to the cup before we only taste milk? If we add one cup of milk to our cup of black coffee (allowing it to overflow) the result will still be a tan cup.
In fact, due to mixing it will be just two thirds milk. We would need to add three cups of milk to get our original black coffee cup to be 95% milk.
Indoor air behaves the same way. As outdoor air enters an indoor space it mixes with the air already indoors.
Indoor air behaves the same way. As outdoor air enters an indoor space it mixes with the air already indoors.
So how long does it take to replace aerosol laden air from indoor spaces with outdoor air? In residences, 95% of the indoor air will likely be replaced with outdoor air in a time frame that ranges from 30 minutes (leaky house) to 10 hours (tight house).
In public buildings, 95% replacement may take between 12 minutes to 2 hours. In a hospital, 95% replacement might take 5 minutes.
So how long an airborne virus stays in the air indoors is highly dependent upon the indoor environment.
So how long an airborne virus stays in the air indoors is highly dependent upon the indoor environment.
