Editing Dew point (section)

==Relationship to human comfort==
When the air temperature is high, the human body uses the evaporation of perspiration to cool down, with the cooling effect directly related to how fast the perspiration evaporates. The rate at which perspiration can evaporate depends on how much moisture is in the air and how much moisture the air can hold. If the air is already saturated with moisture (humid), perspiration will not evaporate. The body's [[thermoregulation]] will produce perspiration in an effort to keep the body at its normal temperature even when the rate at which it is producing sweat exceeds the evaporation rate, so one can become coated with sweat on humid days even without generating additional body heat (such as by exercising).

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, thereby increasing comfort. By contrast, comfort decreases as unevaporated perspiration increases.

A [[wet bulb thermometer]] also uses [[evaporative cooling]], so it provides a good measure for use in evaluating comfort level.

Discomfort also exists when the dew point is very low (below around {{convert|-5|°C|°F|disp=or}}).{{citation needed|date=November 2016}} 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 {{convert|20|-|24.5|C|F|0}} with a 20–60% relative humidity,<ref>{{Cite web|url=https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=interpretations&p_id=24602|title=02/24/2003 - Reiteration of Existing OSHA Policy on Indoor Air Quality: Office Temperature/Humidity and Environmental Tobacco Smoke. |website=Occupational Safety and Health Administration |access-date=2020-01-20}}</ref> equivalent to a dew point of approximately {{convert|4.0|to|16.5|C|F|0}} (by Simple Rule calculation below).

Lower dew points, less than {{convert|10|°C|°F}}, correlate with lower ambient temperatures and cause the body to require less cooling. A lower dew point can go along with a high temperature only at extremely low relative humidity, allowing for relatively effective cooling.

People inhabiting [[tropical climate|tropical]] and [[humid subtropical climate|subtropical]] climates acclimatize somewhat to higher dew points. Thus, a resident of [[Singapore]] or [[Miami]], for example, might have a higher threshold for discomfort than a resident of a temperate climate like [[London]] or [[Chicago]]. People accustomed to temperate climates often begin to feel uncomfortable when the dew point gets above {{convert|15|C|F}}, while others might find dew points up to {{convert|18|C|F}} comfortable. Most inhabitants of temperate areas will consider dew points above {{convert|21|°C|°F}} oppressive and tropical-like, while inhabitants of hot and humid areas may not find this uncomfortable. Thermal comfort depends not just on physical environmental factors, but also on psychological factors.<ref>{{cite journal|last1=Lin|first1=Tzu-Ping|title=Thermal perception, adaptation and attendance in a public square in hot and humid regions|journal=Building and Environment|date=10 February 2009|volume=44|issue=10|pages=2017–2026|doi=10.1016/j.buildenv.2009.02.004|bibcode=2009BuEnv..44.2017L }}</ref>