An indoor humidity level of between 40-60%RH has been scientifically proven to combat airborne flu infections. This ideal humidity level shortens the time airborne flu remains infectious.
The scientific studies below are just a few of the many that show how the correct indoor humidity is vital for airborne infection control.
During the cold winter months, when heating systems dry the air, indoor humidity often drops into the dry danger zone of less than 40%RH. This results in more flu and respiratory infections spreading in the indoor air we all share.
Using humidifiers to put moisture into an atmosphere is only way to ensure the ideal indoor humidity is maintained throughout the winter.
40-60%RH is the ideal indoor air humidity. At this level, the airborne flu virus is quickly inactivated and air humidity is below the level that promotes mould growth.
Dr.med Walter Hugentobler
The science behind humidity's fight with flu
Noti et al 20131 Manikin experiment
Method:Manikins “coughed” flu from nebulizers into a room at different humidity levels. Air samplers collected aerosol particles to assess their continued infectious nature.
Summary result: Flu retains its infectious nature in dry air below 40%RH up to five times longer than in air above 40%RH.
1 – Noti et al, 2013, High humidity leads to loss of infectious influenza virus from simulated coughs, PLoS One. 2013; 8 (2):e57485 2 – Yang et al 2012, Relationship between Humidity and Influenza A Viability in Droplets and Implications for Influenza’s Seasonality, PLoS ONE 7(10): e46789 3 – Lowen et al, 2007, Influenza virus transmission is dependent on relative humidity and temperature, PLoS One Pathogens Okt. 2007/Vol. 3/Issue 10/e151 4 – Sale, 1972, Humidification to reduce respiratory illnesses in nursery school children, Southern Medical Journal, July 1972, Vol. 65, No 7 5 – Gelperin, 1973, Humidification and Upper Respiratory Infection Incidence, Heating, Piping and Air Conditioning, Vol. 45, No.3 6 – Green, 1981, Winter humidities and related absenteeism in Canadian hospitals, Digest of the 3rd CMBFS Canadian Clinical Engineering Conference