How Hot Weather Affects the Human Body

Extended periods of hot weather will do damage to the human body from mild inflammation to possibly life-altering illness. With temperatures ever increasing on so much of the globe as a result of global warming, health professionals are alerting the public to take notice and make choices to guard against it, particularly those most vulnerable to heat sickness.

The instant that the body begins to overheat, its internal air conditioning system kicks in. The blood vessels dilate so that the body can radiate heat to the skin, and the body starts to perspire so that the core body temperature, normally 37°C, can be maintained. But the larger the loss of salt and water through sweating, and the larger loss of blood pressure through relaxation of vessels, the more acute will be the shortage of liquids that the body will begin to experience, and will be unable to perform even simple physiological activities.

Heat exhaustion is a common result of prolonged heat exposure. Symptoms may be anything from dizziness, nausea, and muscle cramps to confusion, profuse sweating, headache, and fatigue. Seizures, loss of consciousness, and death may result if heatstroke is not treated. Heatstroke victims will be unable to sweat and can reach core temperatures of above 40°C. Seek medical assistance immediately if symptoms persist for more than 30 minutes or worsen.

There are certain groups within the community which are particularly susceptible to heat weather. These include the elderly, babies, the sick with pre-existing illness, e.g., heart disease or diabetes, and those with neurological illness, e.g., dementia. Housebound or those with mobility problems are also at risk as are those living on upper floors of flats where the inside will become hotter sooner.

Drugs also predispose patients to heat illness. Diuretics, for example, which are notoriously used in treating heart failure, promote loss of fluids and susceptibility to dehydration. Antihypertensives, which reduce blood pressure, disrupt the body's own cooling system and induce catastrophic drops in blood pressure. Some of the drugs employed in Parkinson's disease and epilepsy close down the body's sweat system. Lithium and statins, however, other medications are dangerous in the situation where the body is not hydrated and the concentration of blood is increased.

According to UK Health Security Agency (UKHSA) guidelines, it is important to take care and keep an eye on the people who cannot control their body temperature. Sun rooms must be closed, don't venture out between 11:00 to 15:00 hours, consume lots of water, minimize alcohol intake, and wear light, loose garments. Sun protection in the form of high-SPF sun cream, wide brimmed hats, and staying in the shade will prevent onset of heat illness.

For those on the outside or who are outsiders, water should be drunk and exercise restricted to the time of the day when the temperature is highest. During heatwaves or urbanization, urban heat effect might lead to amplified temperatures, and this becomes a danger to city residents. Exercise shouldn't leave behind vulnerable groups, such as animals or children, behind parked cars in the sun where temperatures reach very high.

If he or she is showing signs of heat exhaustion, he or she will be relocated to a shaded area, seated with elevated legs, and given hydration. Evaporative cooling with water, fans, or cold compresses to the armpit and neck also works. Resolution at 30 minutes generally comes in the form of a prolonged heat exhaustion state. If there is no improvement, then heatstroke, which calls for emergent medical attention.

Statistics published in 2022, the year England's record all-time high of 40.3°C was recorded, indicate that approximately 2,985 excess deaths from heatwaves occurred. They tend to be caused by complications like heart attacks and strokes, whose incidence is heightened by the body's attempt at maintaining internal temperatures constant. Interestingly, risk of death is extremely contagious in the initial phases of heatwaves, as a rule of thumb within a period of 24 hours, particularly when occurring during spring or early summer when individuals have not yet adapted to the heat.
The health authorities also caution against cooling off in rivers and open water without checking local warning signs, since such waters often possess concealed dangers. Safety protocols need to go beyond individual behavior to encompass public campaigns and infrastructural changes to prepare for more intense and frequent heat spells.

Knowing how the body reacts to heat and being in a position to spot early warning signs of heat illness can avoid serious consequences. Public education and rapid intervention are necessary to mitigate the effects of severe heat, especially with global temperatures on the rise.

Information from James Gallagher, BBC Health and Science Correspondent, and NHS and UKHSA guidelines have been used to write this article.