Keeping indoor humidity levels at a "sweet spot" may reduce spread of COVID-19

The term relative humidity is the amount of moisture in the air compared to the total moisture the air can hold at a given temperature before saturating and forming condensation.

In a study appearing in the Journal of the Royal Society Interface, it reports that maintaining an indoor relative humidity between 40 and 60 percent is associated with relatively lower rates of Covid-19 infections and deaths, while indoor conditions outside this range are associated with worse Covid-19 outcomes. To put this into perspective, most people are comfortable between 30 and 50 percent relative humidity, and an airplane cabin is at around 20 percent relative humidity.

The findings are based on the team's analysis of Covid-19 data combined with meteorological measurements from 121 countries. Their study suggests a strong connection between regional outbreaks and indoor relative humidity.

Indoor ventilation is still critical, however, the researchers found that maintaining an indoor relative humidity in that sweet spot - of 40 to 60 percent - is associated with reduced Covid-19 cases and deaths.

Reference:

Keeping indoor humidity levels at a "sweet spot" may reduce spread of COVID-19; MASSACHUSETTS INSTITUTE OF TECHNOLOGY, Journal of The Royal Society Interface.