Why should indoor relative humidity be maintained between 45-50%?
Studies conducted in the 1980s By E.M Sterling, A. Arndel and T. D Sterling suggested that the optimal conditions to minimize risk to human health occur in the narrow range between 40 – 60% relative humidity. “Criteria for Human Exposure to Humidity in Occupied Buildings” was reported in the ASHRAE Transactions 1985 Vol. 91 Part 1. Allergens such as dust mites and fungi which cause allergic rhinitis and asthma were eliminated at relative humidity below 50%.
