The short answer
Indoor humidity that is too low or too high can affect breathing comfort. A commonly discussed target range is roughly 30–50% relative humidity, though individual preferences vary and your care team may have specific guidance. A hygrometer — an inexpensive device that measures humidity — is the simplest way to check.1
Why humidity matters
Air that is very dry can dry out the airways and thicken mucus, which may make coughing more effortful. Air that is very humid can feel heavier and, in some environments, encourage mould growth — a recognized airway irritant.
Humidity also interacts with temperature. Warm air holds more moisture than cool air, which is why the same absolute amount of water vapor can produce different relative humidity readings at different temperatures. This is one reason humidity can feel different in winter and summer, even indoors.
A common range
| Relative humidity | Possible implications |
|---|---|
| Below 30% | Air may feel dry; airways and skin may feel dry; static electricity common. |
| 30–50% | Commonly recommended range for indoor comfort and respiratory health. |
| 50–60% | May feel humid to some; mould risk begins to rise, especially above 60%. |
| Above 60% | Increased mould and dust mite risk; may feel heavy. |
This range is a general reference, not a medical prescription. Some people find they are more comfortable at one end of the range than the other.
Measuring humidity
A hygrometer is a small device that displays relative humidity. Many also display temperature. They are widely available and inexpensive. Placement matters: a hygrometer near a window, a bathroom door, or a kitchen may give readings that differ from the middle of a living room.
Some people use a single hygrometer and move it between rooms to get a sense of variation. Others place one in the bedroom and one in the main living area. There is no single right approach — the goal is to know roughly where you are.
Adjusting humidity
If humidity is persistently outside the range you are aiming for, some options are commonly discussed:
- Using a humidifier if the air is too dry — particularly in winter or in heated homes.
- Using a dehumidifier if the air is too humid — particularly in basements or coastal climates.
- Improving ventilation, which can help regulate humidity naturally.
- Addressing leaks, damp, or poor drainage that contribute to excess moisture.
- Drying laundry outdoors or in a ventilated space rather than indoors.
Humidifiers and dehumidifiers require cleaning and maintenance. A humidifier that is not kept clean can itself become a source of particles or microbial growth.
For related reading, see our guide The Home Air Review and our article Cold Air, Humidity, and Changing Weather.
What to discuss with your care team
- Is there a humidity range you would suggest I aim for indoors?
- Would a humidifier or dehumidifier be worth considering in my case?
- Are there signs of damp or mould I should have checked?
- Should I track humidity alongside my symptoms?
- Are there maintenance considerations for humidifiers I should know about?
Sources
- U.S. Environmental Protection Agency. Humidity and Indoor Air Quality.
- Centers for Disease Control and Prevention. Indoor Air Quality and Health.
- American Lung Association. Humidity and Lung Health.
- National Heart, Lung, and Blood Institute. COPD: Living With COPD.