Building occupants are being exposed to increased risk from viruses, such as the coronavirus, because the regulations on indoor air quality (IAQ) are falling short of current scientific knowledge. Maintaining IAQ at above 40%RH has been scientifically shown to reduce viral cross infection, including coronavirus and influenza. Yet out-of-date regulations on the topic result in buildings such as hospitals, offices and schools experiencing dangerously low humidity levels every winter.

Studies, such as Casanova et al 20101, have specifically examined humidity’s role in coronavirus transmission. This study showed that coronavirus was deactivated fastest when exposed to a mid-range humidity (50%RH), rather than dry (20%RH) or damp (80%RH) air. There are many other studies, dating back from the 40s to now, that all indicate that an indoor humidity of 40-60%RH has a positive impact on cross infection and people’s susceptibility to viruses. Alongside Casanova et al 2010, summaries of 25 other such studies are listed on our website.

To learn more about the role humidification plays in virus transmission, browse through the resources below.