Home Humidifiers as a Potential Source of Exposure to Microbial Pathogens, Endotoxins, and Allergens

Publisher Website
Google Scholar
Abstract
The propensity of various types of home humidifiers to support and disseminate microbial contaminants into indoor air was tested. Reservoir water and air discharged from humidifiers seeded in the laboratory or naturally contaminated in the home were analyzed by standard microbiological methods. Clinically insignificant as well as overt or potentially pathogenic microorganisms were found to colonize the reservoirs of all types of humidifiers, but only cool mist and ultrasonic units readily aerosolized bacteria and endotoxin. Only cool mist units emitted hydrophobic fungal spores. Cool mist units discharged the greatest number of water particles in the inhalabk size range (4–16 μm) while ultrasonic units were more likely to emit respirable-sized water particles (< 0.2–4 μm). Overt pathogens isolated from humidifiers in homes included Legionella and a pathogenic Acanthamoeba. Aerosolizing humidifiers should thus be avoided if frequent, thorough cleaning of the units is not practical.