What is an Ideal Air Humidity Level for Health?

The definition of “ideal” means something different to everyone and ideal humidity level in the home is no exception.


While the United States Environmental Protection Agency (EPA) has no humidity percentage standard, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) suggests staying within the following guidelines:

  • Indoor temperatures in the winter be maintained between 68 degrees and 75 degrees, with a relative humidity level between 30 percent and 60 percent
  • Temperatures in the summer should be maintained between 73 degrees and 79 degrees, with a relative humidity level between 30 percent and 60 percent

Let’s examine what relative humidity means and how it affects comfort. The definition of relative humidity according to the Air Conditioning Contractors of America is “the ratio of water vapor currently in the air to the maximum water vapor at that temperature, multiplied by 100.”

Plainly, air at high temperatures holds more water vapor.

But what happens in the winter when temperatures drop and the air lacks moisture? Your heating unit warms the air but does not add water to the indoor atmosphere. This is exactly when the need for added (and regulated) humidity comes into play.

Now, let’s consider what is environmentally agreeable for one person residing in a home or office might not be the same to another. The Illinois Department of Public Health (IDPH) states many factors like activity level and clothing can also be a factor in “optimal temperature”.

“Acceptable relative humidity levels should range from 20 percent to 60 percent year-round,” states the office of the IDPH. “Levels less than 20 percent in the winter and greater than 60 percent in the summer should be considered unacceptable.”

Why are these levels unsatisfactory? Because high levels of relative humidity promotes the growth of elements like bacteria and mold and creates an environment where dust mites can thrive. If you are plagued by allergies, an excessive amount of humidity will be detrimental to your health.

On the flip-side, if the humidity is too low, other concerns like dry, itchy skin and the irritation of the upper respiratory system can become more than just irritating. Frequent exposure to dry air can bring on bloody noses and chronic chapping of the lips, skin and throat.

Taking into consideration that everyone and everything in the home needs a stable level of humidity, it’s probably best to bring in a humidifier that will do the job and give you peace of mind at the same time. Our Airwasher works by pulling indoor air into the machine, and cleaning it to remove particles and allergens. Functioning without the use of filter pads, the dirty water is collected. Contaminants in the air, like old tobacco smoke, household dust, pollen and allergens are trapped in the water, with clean, humidified air evaporating back into the room. Plus – the humidity is regulated based on your unique environment.

If you are wondering what the humidity level is in your home during this time of year based on your specific location, try the indoor humidity meter from Weather.com. 

Easy breezy!