By Judith Green, Co-Chair, Climate Change, North Jersey Group
The longer seasons of more frequent and severe heat waves pose new dangers. Heat-related hospitalizations for heart attacks and dehydration are on the rise in the United States, and heat-related deaths are mounting. We need to be aware of the dangers of these trends for our health and survival.
The past 10 years have been the hottest years on record, and summers now see many heat events described as “extreme.” Humans have adapted to climate changes over the millennia, but the current shifts are happening with unprecedented speed and severity. We are threatened by heat stress, and some of us are more vulnerable. What can we do to protect ourselves?
The Basics
In a hot environment, the two main mechanisms we have to maintain our body temperature at about 98.6° F are perspiration, which cools the body through evaporation, and cardiovascular adjustments, which move warm blood to the body’s surface so heat can dissipate into the surrounding air.
Perspiration is our most efficient mechanism for losing heat. Because evaporation releases heat in the form of vapor, perspiring allows for evaporative cooling to occur over the body’s surfaces. In dry climates evaporation occurs readily and perspiring is very effective for cooling. However, in humid environments, sweat evaporates slowly or not at all, reducing its cooling impact.
In hot environments, our cardiovascular system causes the heart to beat harder and faster to deliver more warm core blood to vessels at the body’s surface, where the skin’s blood vessels dilate to more effectively transfer this heat into the surrounding cooler air. Reddish or pinkish “flushed” skin in hot settings is visible evidence of cutaneous blood vessels dilating.
When humidity is high and perspiration is ineffective, we depend on air that’s cooler than skin temperature to wick away the heat from dilated blood vessels. In extreme heat, however, when the air is as warm as—or warmer than—the skin, the body can no longer release heat, preventing cooling through blood flow to the surface. Thus, when temperature and humidity are both high, adequate cooling doesn’t occur, and the body overheats. This situation is dangerous, because biological processes break down when the body’s temperature elevates.
Indicators of Overheating
When outdoors on very hot days, it’s important to watch for the following signs of heat exhaustion:
- Weakness
- Dizziness
- Fainting
- High body temperature
- Excessive sweating
- Nausea
- Paleness
- Cool clammy skin
- A rapid, weak pulse
Evidence of heat exhaustion would signal the need for immediate action to prevent progression to life-threatening heat stroke.
At a minimum, an appropriate response includes moving to a cooler or shadier environment, ceasing all strenuous activity (muscle activity generates heat), applying damp cloths, removing excess clothing, and replenishing water and electrolytes. Medical attention may be needed.
Heat stroke is uncontrolled body heating that generally occurs when body temperature exceeds 104° F, accompanied by signs of severe heat illness, such as confusion; agitation or strange behavior; redness; hot, dry skin; nausea; and seizure or coma. Immediate medical help and cooling are required. If assistance is not available, apply icepacks or submerge the person in cool water.
Age and Heat
Data indicate that heat-related deaths in the United States are rising dramatically, and most heat-related deaths occur in people over 50. In a 2022 heat wave in Europe, people 65 and older accounted for 90% of heat-related deaths.
As we age, our bodies’ primary cooling mechanisms lose efficiency. Notably, sweat glands secrete less fluid for a given heat challenge, reducing our evaporative cooling capacity. Further, older people have a dulled sense of thirst, which impedes compensation for heat-related water loss.
Sweating increases the risk of dehydration. With age, it’s important to cultivate drinking as a conscious and purposeful behavior, going beyond mere slaking of thirst, especially in hot weather.
Cardiovascular cooling, too, may be compromised in the elderly, posing dangers for them. Aging hearts may be unable to speed up when needed or be otherwise impaired by disease.
The strain when pumping harder to move blood briskly through expanded surface vessels contributes to heart attacks, arrhythmias, and strokes that occur more frequently among older people during heat waves. Also, medications taken more often by the elderly can interfere with heat management mechanisms.
Chronic diseases are more common in older people, adding to the risks of aging in a hotter world.
Heat Extremes and Pregnancy
Since the developing fetus itself generates heat, pregnant women experience greater heat stress. Heat exposure during pregnancy is strongly linked to premature birth, with as much as a 16% increase during heat waves.
Elevated infant mortality, delayed development, learning and behavioral disorders, and a higher risk of chronic diseases later in life are all associated with prematurity. Research suggests that the mother herself is at greater risk for gestational diabetes, high blood pressure, and complications during labor. Although safe limits for heat exposure during pregnancy are not yet known, caution is prudent.
Surviving a Hotter World
Arrange to be indoors or minimally active during the hottest parts of the day, thereby avoiding the heating effects of direct sunlight. Preemptively drink more fluids and electrolyte beverages to maintain your salt and water balance; wear loose-fitting, light-colored reflective clothing; keep a small battery-operated fan handy; and rest often to cool off when active. In urban areas, community-level coping includes planting more trees and painting roofs and sidewalks white.
Taking such precautions may provide other benefits, too. A recent study found that people from extremely hot parts of the country tended to look 14 months older biologically than people in cooler parts of the country. So, protecting yourself from heat events may keep you looking youthful!
Disclaimer: The author is not a physician. Seek professional medical advice and help if not feeling well in a hot environment.