Abstract

Authors reviewed scientific literature that focused on humidity effects on biological contaminants (viruses, bacteria and fungi) causing respiratory disease, chemical interactions and the possible impacts on human health and comfort. 74 references are listed in the paper.

Analysis of the selected literature revealed that preferences of viruses and bacteria for low and high humidity are known, while fungi prefer humidity’s above 80%RH for optimal survival on surfaces. For airborne microbes, literature revealed, that midrange humidity was least favourable for survival. Interventional clinical trials by use of humidifiers were analysed for rates for respiratory infections and absenteeism.

While off-gassing of formaldehyde and chemical interactions increases above 40%RH, the concentration of irritating ozone decreases.

Conclusion

The authors conclude that the optimal humidity range for minimizing risks to human health by biological contaminants and chemical interactions, is in the narrow range between 40-60%RH, at normal room temperatures.