<P> As the air surrounding one's body is warmed by body heat, it will rise and be replaced with other air . If air is moved away from one's body with a natural breeze or a fan, sweat will evaporate faster, making perspiration more effective at cooling the body . The more unevaporated perspiration, the greater the discomfort . </P> <P> A wet bulb thermometer also uses evaporative cooling, so it provides a good measure for use in evaluating comfort level . </P> <P> Discomfort also exists when the dew point is low (below around − 30 ° C or − 22 ° F). The drier air can cause skin to crack and become irritated more easily . It will also dry out the airways . The US Occupational Safety and Health Administration recommends indoor air be maintained at 20--24.5 ° C (68--76 ° F) with a 20--60% relative humidity, equivalent to a dew point of − 4.5 to 15.5 ° C (24 to 60 ° F). </P> <P> Lower dew points, less than 10 ° C (50 ° F), correlate with lower ambient temperatures and the body requires less cooling . A lower dew point can go along with a high temperature only at extremely low relative humidity, allowing for relatively effective cooling . </P>

What is the dew point of dry air
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