How Healthy Humidity Levels In Your Home Can Protect You

A healthy humidity level inside your home doesn’t just happen naturally. Just as you usually wouldn’t be comfortable simply letting the indoor temperature match outdoor readings, leaving indoor humidity to chance isn’t a strategy for a healthy, comfortable indoor environment, either.

The interaction between water vapor in the air and a healthy home occurs at both low and high humidity levels.

  • Airborne particulates like bacteria, spores and viruses are more active at certain humidity levels. Colds and flu viruses, for example, actually thrive in dry environments where relative humidity is 35% or lower. Mold spores and active mold growth, conversely, as well as certain bacteria types, are activated when humidity rises above 50%.  When humidity is maintained within the 35% to 50% target range, allergic symptoms, respiratory illness and other heath issues may be reduced.
  • Indoor humidity is also linked to increased levels of gases known as volatile organic compounds (VOCs). These substances—formaldehyde is the best-known example—are ingredients in many building materials as well as carpeting, paint and furniture. When exposed to indoor humidity above 50% for extended time periods, many of these products emit higher levels of VOCs into the air you breathe. Long-term exposure to volatile organic compounds is a known health risk.  

When Humidity Is Too Low …

Low indoor humidity often occurs in dry winter conditions. Gas-fired heating dries indoor air further, causing humidity levels to drop into the unhealthy range. Use of individual room humidifiers—or installing a whole-house humidifier that adds water vapor to the HVAC airflow to maintain precise indoor humidity levels—are the best recourse to keep the indoor environment healthy.

When Humidity Is Too High …

Indoor humidity above 50% is often related to a naturally humid outdoor climate. To keep the indoor environment drier and healthier, these methods are helpful.

  • Air-sealing the home to reduce infiltration of moist outdoor air.
  • Installing a whole-house dehumidifier in the HVAC system to control humidity.
  • Annual maintenance check-up of the central air conditioner to ensure that the unit’s humidity extraction function is operating up to specs.
  • Installing exhaust fans in kitchens and bathrooms where water vapor originates.

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