Humidity is the amount of water vapor in the air - whether you are indoors or outdoors. Higher humidity can make you feel hot and sticky, while lower humidity can make your skin, lips, and eyes feel dry.

Among other things, the American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) sets indoor humidity standards and guidelines. They say that anything above 60% is considered high indoor humidity.

The Environmental Protection Agency (EPA) recommends indoor humidity levels between 30-50% for optimal comfort. Between 30-45% in the winter should keep you warm and comfortable while between 40-50% in the summer should provide a comfortable home.

Humidity levels that are outside the optimal range can potentially negatively impact your home, your health, and your indoor air quality (IAQ). High humidity can provide an environment for mold, mildew, and dust mites to thrive. This can exacerbate allergies and make it harder for people with asthma to breathe. 

By contrast, low humidity can allow bacteria, viruses, and other pollutants to move more freely in the air. Keeping the indoor humidity levels between 40-50% can help prevent respiratory infections caused by bacteria and viruses.

The best way to achieve the ideal indoor humidity at home is by investing in a whole-house humidifier or dehumidifier, depending on the issues you are experiencing. Humidifiers and dehumidifiers work behind the scenes to keep your home at optimal humidity levels, so you don't have to think about your home's humidity. 

You can measure and monitor their indoor humidity levels with a digital humidity meter (hygrometer) which you can find at most hardware stores.

A dehumidifier removes excess humidity from the air in your home. It can boost the effectiveness of an older air conditioner, and reduce humidity levels year-round, even when you don’t need the cooling from your AC.  

A whole-house dehumidifier works sort of like your air conditioner, in that it cools the air to remove moisture. It draws warm, moist air over an evaporator coil. The coil contains refrigerant to help cool the air. As the air cools, it produces condensation, which collects at the bottom of the coil and eventually drains into a reservoir, and eventually drains out of your home through a drain line.

Your home could likely benefit from the installation of a whole-home dehumidifier if any of the following are true.

• Your house feels damp and sticky - not just the basement.
• Your home smells musty.
• You have problems with mold and mildew growth.
• Wood warps and metal rusts easily.
• You have a lot of spiders and creepy crawlies.
• Allergies and asthma are exacerbated.
• Your single-stage air conditioner runs constantly but the humidity is still high.
• You have condensation on the inside of your windows.
• You live in a humid climate.