The Impact of High Relative Humidity on the Body, and Why It Feels More Uncomfortable Than Dry Heat
In the sweltering heat of summer, the combination of high temperatures and humidity can pose a significant threat to our health. This article explores the impact of humidity on the human body and the risks associated with it.
Heat rash, a skin condition caused by inflammation of sweat ducts, can develop due to lingering sweat caused by high humidity[1]. When the body temperature rises, it sweats to cool down. However, at humidity levels above 75-80%, sweating becomes less effective at cooling the body because the air is already saturated with moisture, preventing evaporation and heat loss[1][3]. This reduced sweat evaporation significantly impairs the human body's ability to regulate temperature, leading to increased core body temperature[1][2][3].
High core body temperature can strain the body, particularly the cardiovascular system. To dissipate heat, blood vessels dilate and send blood to the skin surface. However, this reduces blood flow to vital organs, increasing the risk of dehydration, kidney injury, and cardiovascular stress, especially in vulnerable populations like older adults and those with chronic diseases[3][5].
The body normally maintains a core temperature near 37°C (98.6°F), but high humidity coupled with heat can raise core temperature above safe levels, increasing the risk of heat-related illnesses[1][2][3]. These conditions range from heat exhaustion, a state of dehydration and overheating, to heat stroke, a life-threatening illness that occurs when the body remains too hot for a prolonged period[2][3].
Recent experimental data show that healthy young adults face physiological heat tolerance limits at a wet bulb temperature around 31°C (87°F) at 100% humidity—lower than previously thought 35°C (95°F)—meaning that dangerous conditions are already occurring in some regions[1]. Elderly individuals, young children, and those with preexisting conditions or on certain medications are especially vulnerable because their temperature regulation and thirst mechanisms are impaired[5].
Dry air helps in evaporating sweat, cooling the body down. Conversely, high relative humidity can exacerbate dehydration due to difficulty in evaporating sweat[4]. Excessive sweating can occur when the body cannot cool down due to high relative humidity. This excessive sweating can lead to a variety of conditions including fatigue, muscle cramps, dizziness, heat rash, heat exhaustion, and heat stroke[6].
In summary, high relative humidity compromises sweat evaporation, prevents effective body cooling, raises core temperature, and thereby heightens the risk of heat-related illnesses such as heat exhaustion, heat stroke, kidney failure, heart attack, and even death[1][3][5]. Public health measures and individual precautions become vital under these conditions to prevent heat-related morbidity and mortality[1][3][5].
[1] NOAA National Weather Service. (2021). Heat Index. Retrieved from https://www.weather.gov/heat
[2] Mayo Clinic. (2021). Heat exhaustion. Retrieved from https://www.mayoclinic.org/diseases-conditions/heat-exhaustion/symptoms-causes/syc-20376483
[3] National Institute of Environmental Health Sciences. (2021). Heat-Related Illnesses. Retrieved from https://www.niehs.nih.gov/health/topics/conditions/heat/index.cfm
[4] National Weather Service. (2021). Absolute Humidity. Retrieved from https://www.weather.gov/om/glossary/ah
[5] Centers for Disease Control and Prevention. (2021). Extreme Heat: Older Adults. Retrieved from https://www.cdc.gov/disasters/extremeheat/olderadults.html
[6] American Academy of Dermatology. (2021). Heat Rash. Retrieved from https://www.aad.org/public/diseases/a-z/heat-rash-topic-overview
- In the realm of science and health-and-wellness, high humidity hinders sweat evaporation, leading to ineffective body cooling, elevated core temperature, and an increased risk of heat-related illnesses such as heat exhaustion and heat stroke.
- In the context of fitness-and-exercise, the combination of sweat and high humidity can exacerbate dehydration, causing fatigue, muscle cramps, dizziness, and a variety of other conditions.
- From the perspective of mental-health, therapies-and-treatments may be necessary to cope with the stress and discomfort caused by excessive sweating, heat-related illnesses, or heatwaves.
