Humidity and Your Health

The Wellbuilt for Wellbeing study (sponsored by the US General Services Administration in partnership with the University of Arizona, Baylor College of Medicine, and Aclima Inc.) was designed to explore the influence of the office environment on human health, comfort, and performance. We used sensors to explore interactions between human health and the widest range of indoor environmental factors ever captured in the field in real time. We found that office workers who spent the majority of their time in dry air experienced 25% more stress than those in moderate humidity. We also found higher stress for those spending most of their time in very humid air suggesting a sweet spot in the middle. Those who experienced lower stress at work also slept better at night.

Avoiding dry air has a number of health benefits. Getting better sleep and reducing stress is important to long term health and wellbeing, as well as reducing susceptibility to viruses. Chronic stress is known to increase frequency and severity of viral infection. Dry air can degrade the eye’s tear film and mucous membranes in skin and airways in a matter of minutes making them more susceptible to inflammation. It also contributes to dehydration through direct transfer of water or “insensate” loss from the skin to the air. Dehydration persisting a few hours causes fatigue and makes it harder to concentrate.

Dry air may also increase the risk of transmission of many viruses, including those of the coronavirus family, but these mechanisms are complex and poorly understood. Dry air degrades mucosal membranes in the nose and upper respiratory tract making them more susceptible to infection and allows viruses to survive and the particles that carry them to stay suspended longer in the air. As such, managing humidity could be one of many strategies to manage the risk of Covid-19 infection in concert with those identified by the Centers for Disease Control and Prevention.

Getting better sleep and reducing stress is important to long term health and wellbeing, as well as reducing susceptibility to viruses.

Eliminating dry air should be part of a broad strategy to improve indoor environments. Most buildings are designed to heat or cool air to a consistent temperature to make most people comfortable. However, people have very diverse personal preferences so this strategy leaves many unhappy. In one study, as few as 11% of commercial office buildings in the US met the target for satisfaction established by the American Society of Heating, Refrigeration, and Air-Conditioning Engineers. Using alternative design strategies as buildings are built or renovated can help manage humidity and provide comfort to more people. Unfortunately, getting rid of dry air in existing buildings often requires adding humidification. This is impractical in buildings with poor insulation or very cold climates where a risk of indoor condensation on windows and walls could lead to mold growth.

As a result, it is important to consider both building design and promoting simple behavioral changes when considering how to address dry air:

• Humidify air to 40-60% relative humidity where the climate and the building allow it.
• Consider radiant heat and cooling instead of forced-air systems in new construction.
• Encourage employees to take “micro-breaks” of 10-20 seconds every half hour where they look away from the computer and blink to avoid dry eyes.
• Encourage longer breaks every hour to drink water and rehydrate to avoid fatigue.

Photo via Getty Images

By Javad Razjouyan, PhD and Brian Gilligan, PE for the Wellbuilt for Wellbeing Project Team