ASK TOM: What indoor humidity level is recommended during the winter?

Dear Tom,

What indoor humidity level is recommended during the winter?

— Ron Chapman, Madison, Wis.


Dear Ron,
The American Society of Heating, Refrigerating and Air-Conditioning Engineers recommends an indoor relative humidity at added1 of about half of the indoor temperature. If you heat your home house to 70 degrees, the recommended humidity level is 35 percent. A temperature of 70 to 74 degrees is comfortable For most people, 70 to 74 degrees temperatures are is comfortable, but when cold outside air is warmed to that level without added1 adding the addition of moisture, indoor relative humidity levels plunges.
Moisture should be added to indoor air when outdoor temperatures fall drop into the 30s or lower because the air can become “desert- dry,” with its relative humidity falling below 10 percent. Static electricity flourishes when this happens and many people experience dry skin and respiratory discomfort.