Criteria for Human Exposure to Humidity in Occupied Buildings
The Authors of the referenced document have reviewed health literature of relevant biological and chemical interactions in order to define an optimal range of humidity where overall risk may be minimized. Humidity effects (within a normal indoor temperature range of 19 degree Celsius to 27 degree Celsius) are reviewed for three groups of factors.
- Biological Contaminants including bacteria, viruses, fungi and mites.
- Pathogens causing respiratory problems including respiratory infections, allergic rhinitis and asthma, and hypersensitivity pneumonitis.
- Chemical interaction including Ozone production.
Below picture showcases the optimal humidity level depicted.
After detailed reviewing and analysis scientists have come across an optimal humidity range of 40% to 60% where effects of various biological contaminants are minimal. However, off-gassing of formaldehyde and chemical interactions increases above 40%RH, the concentration of irritating ozone decreases.
At normal room temperature, optimal humidity level is between 40-60% RH. At lower humidity levels it can be seen that bacteria, viruses, respiratory infections and allergic Rhinitis and Asthma have more tendency to affect humans. Also, a higher humidity level also increases the risk for Humans to get affected by earlier mentioned factors. Thus the rate of infections etc. can be lowered if we maintain the indoor humidity level in the range of 40-60% RH.