Sunday, July 14, 2024


“You may choose to look the other way, but you can never say again that you did not know.”

— William Wilberforce


Higher Humidity in Buildings Can Help Lower Infections


Harvard Medical School graduate and pediatric oncologist Stephanie Taylor, MD once took care of children with cancer at a teaching hospital. She wondered why many of her young patients contracted infections, such as influenza, despite the hospital’s heavy emphasis on prevention. Taylor began to suspect increased susceptibility to contracting infections might have something to do with the design and infrastructure of the building itself.1

Current hospital infection control protocols focus largely on hand washing, instrument disinfection, and surface hygiene, cough etiquette and use of facial masks. These strategies mainly target the interruption of transmission through body contact and exposure to short distance, large-droplet spray. Most infection control strategies do not address the need to immobilize tiny, aerosolized droplets, which can spread infectious microorganisms across significant distances and for extended periods through the air.2

Dr. Taylor and her colleagues decided to conduct a study to investigate the impact of the building environment on human health and infection. She and her colleagues studied 370 patients in one unit of a hospital to try to isolate the factors associated with patient infections. They tested and retested 8 million data points controlling for every variable to explain the likelihood of infection.1

Most factors had an influence; however, one factor stood out the most. The leading factor most associated with infection was dry air. At low relative humidity, indoor air was strongly associated with higher infection rates. According to Taylor:

When we dry the air out, droplets and skin flakes carrying viruses and bacteria are launched into the air, traveling far and over long periods of time. The microbes that survive this launching tend to be the ones that cause healthcare-associated infections… Even worse, in addition to this increased exposure to infectious particles, the dry air also harms our natural immune barriers which protect us from infections.1

Dr. Taylor explains:

With new genetic analysis tools, we are finding out that most of the microbes are not dead at all. They are simply dormant while waiting for a source of rehydration. Humans are an ideal source of hydration, since we are basically 60% water. When a tiny infectious particle lands on or in a patient, the pathogen rehydrates and begins the infectious cycle all over again.1

Taylor’s research demonstrates that ideal humidity for indoor air is between 40 percent and 60 percent relative humidity.1 This new evidence could be important for hospitals and other health care facilities, where at least 10 percent of all patients who enter an inpatient health care facility for treatment will develop a health care-associated infection.2

1 Binder L. This Inexpensive Action Lowers Hospital Infections And Protects Against Flu Season. Forbes Oct. 17, 2019.
2 Taylor S, Hugentobler W. Is low indoor humidity a driver for healthcare-associated infections? Harvard Medical School, Boston, Massachusetts, United States & Universität und Universitätsspital Zürich.

3 Responses

  1. I doubt it’s ‘dry air’ that causes the problem. It’s just that air conditioners happen to dry the air while cooling it.

    They need to understand how central air conditioning systems work, and they would realize they are the perfect collection, culturing, and distribution system for germs. I’d be curious to see an investigation of the germs you would find in the evaporator coil drip pans in hospitals!

    Have you been in a hospital that wasn’t kept very cold?

    Also, the medical system, hospitals, pharma drugs etc are NOT ‘healthcare.’ There is nothing health-promoting about the US medical system. Every time I hear this horrific health-damaging system called ‘healthcare’ it’s like fingernails scraping a blackboard.

    Healthcare is good nutrition, excercise, avoiding toxic exposures (including Pharma drugs, vaccines, pesticides, GMOs, junk food, etc). We need to take that word back from the medical system.

    1. Amen to that; though I have found that when humidity gets very low my grandson gets nosebleeds and when it is too high there is more chance for fungal spores to grow so I try to keep it right around 45-55% year round with portable humidifiers. My pet peeve right now is the schools not disinfecting the computer keyboards that are used by hundreds of kids. What a great way to pass the latest bug like wildfire! I offered to buy them Lysol to spray in between users. Worked great at our house when we kept spreading the bug back & forth between us.

  2. I use my cool mist humidifier with distilled water and food grade hydrogen peroxide diluted to 1.5% strength. It releases an extra molecule of oxygen and the air smells clean and fresh–like it is scrubbing it clean. I find it clears my head and helps me to concentrate, too.

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