The Impact of Humidity
on Health & Indoor Conditions


humidity and mold

Understanding the effects of humidity.

Knowing your home’s humidity level is essential to improving indoor air quality and the overall health and comfort of you and your home. To ensure your home’s air quality, the Environmental Protection Agency (EPA) suggests maintaining proper indoor relative humidity (RH) levels to reduce the effects of many of unwanted conditions associated with poor indoor air quality.

What do humidity levels do to us?

Too much humidity can cause an increase in biological pollutants, like mold, bacteria, viruses, fungi, and dust mites that can trigger respiratory health ailments. Too little humidity can lead to nosebleeds, painful skin irritation, difficulty breathing and damaging static electricity.

Maintain a Healthy Balance

If you’re concerned about the humidity level in your home, check it regularly with AcuRite's Digital Humidity & Temperature Monitors. AcuRite's Humidity Monitoring products measure indoor temperature, humidity and some feature a humidity level icon to easily convey a low, high or ideal indoor humidity level for your home and health:

low humidity home comfort

humidity OK for home comfort

humidity HIGH for home comfort

LOW Humidity Level
Less than 25% RH
Humidity level is low relative to the temperature. This makes for a dry environment.


OK Humidity Level
Between 25% - 55% RH
Humidity level is OK relative to the temperature. This makes for a comfortable environment.


HIGH Humidity Level
Over 55% RH
Humidity level is high relative to the temperature. This makes for a humid environment.


Protect your Home & Valuables

Aside from the health effects, extreme levels of humidity can cause permanent damage to your home and furnishings. A hygrometer is an essential tool for homeowners, hobbyists, collectors, musicians and lifestyle enthusiasts concerned with protecting their investment.

• In your home — wood furniture and flooring and can dry out and warp with too little humidity. And with too much persistent humidity, mold and mildew can permanently damage your home leading to costly repairs.

• Stamp collectors — maintaining stable relative humidity will reduce the effects of hydrolysis (repeated de/absorption of water vapors), which ruins your stamps by making them brittle or discolored.

• Photography collectors — high humidity can lead to fading, discoloration, and silvering, as well as mold growth and insect infestations. Extremely low humidity leads to photographs becoming brittle or the emulsion flaking off.

• Art collectors — fluctuations in temperature and humidity can damage artwork over time. Paint cracks, separates, and peels. Paper molds, tears, and fades. Antique veneers separate and warp. Fine papers and textile arts are particularly sensitive.

• Wine enthusiasts — maintaining the correct balance of temperature and humidity preserves your wine collection. Too much humidity and mold can grow and cellar woods and wine labels can be damaged. If your collection is too dry, the cork will crack and air will leak into the bottle ruining the wine.

• Cigar aficionados — the ideal condition for storing cigars is relative humidity of approximately 68-74%. Desirable cigar flavors evolve in these conditions. Dry cigars become fragile and burn faster developing an unpleasant and slightly bitter taste. Damp cigars will burn unevenly and produce a heavy and acidic flavor.

• Musicians — natural wood is still the preferred material used to craft musical instruments because of its pleasing tonal qualities, but all varieties of wood expand and contract with changes in relative humidity. Humidity causes damage to instruments when internal stresses created by expansion or contraction cause glue joints to fail or the wood to crack.

• Indoor gardeners — your plants will love you for maintaining the proper level of humidity. Most houseplants thrive with humidity levels around 60%. Native desert plants prefer a much lower relative humidity (30-35%), while tropical plants favor more moisture (up to 90%).


Further Reading

United States Environmental Protection Agency (EPA)
• Asthma Triggers:
• A Brief Guide to Mold, Moisture and Your Home: or Download the PDF
• Mold and Moisture FAQs:

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This article references information published by the EPA. Retrieved January 10, 2012 from