Dear Tom,
What should the humidity be indoors in the winter months? Is 40 percent too low?
Justin Schmollinger, Chicago
Dear Justin,
A rule of thumb is that most people feel comfortable (in a heated building) when the humidity is about half of the room temperature. If your thermostat is set at 72(degrees), an indoor humidity of 36 percent would be about right. A study conducted by the American Society of Heating, Refrigeration and Air Conditioning Engineers determined that 71-74(degrees) is ideal when the relative humidity is 50-60 percent and there is a slight air movement (but not strong enough to be a draft).
Higher indoor humidities make us feel warmer, but it is not advisable to maintain a winter humidity of 50-60 percent because moisture might condense on windows or inside exterior walls. Fortunately, most people find lower indoor humidities (35-40 percent) to lie within their winter comfort range.
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Tom Skilling is chief meteorologist at WGN-TV. His forecasts can be seen Monday through Friday on WGN-TV News at noon and 9 p.m.
Write to: ASK TOM WHY, 2501 Bradley Pl., Chicago, IL 60618 or asktomwhy@wgntv.com (Mail volume precludes personal response.)
WGN-TV meteorologists Steve Kahn, Richard Koeneman and Paul Dailey plus weather producer Bill Snyder contribute to this page.
