Humidifier use in health care

Many residents of long-term care facilities and retirement homes use portable bedside humidifiers to increase moisture levels in the air inside their rooms. Humidifiers are used to help relieve respiratory symptoms such as shortness of breath, alleviate dry skin; and reduce dryness and irritation to the nose and throat. 

Relative humidity is measured as a percentage of how much water vapor is in the air, compared to how much it could hold at that temperature. While a comfort range of 40%–60% relative humidity has been shown to decrease survival of influenza viruses, a humidity level above 60% should be avoided because it can promote the growth of microorganisms, including mould. 

Humidifiers that atomize water to generate micro-sized droplets in the air (referred to as an aerosol) can potentially distribute any microbial contaminants present in that water or in biofilms that develop on humidifier tanks, reservoirs, and spouts. Contaminated room humidifiers have been linked to both health care-acquired and community-acquired infections.

Given the reported benefits versus the potential for respiratory disorders, the appropriateness of allowing bedside humidifiers for health care patients has been a topic of debate.  Public Health Ontario’s Evidence Brief: Humidifier use in health care explores the various kinds of humidifiers and the the potential risk of their use in health care settings.