Effects of Hot Temperature on the Body
The recent hot winds that have brought in very hot temperature is of great importance. At this time of the year, one would expect the cold dry harmattan winds to be around, but the climate change that is threatening the world, has not spared Nigeria. The usual set pattern in weather has been merged with wild unthinkable conditions. Therefore, the recent onslaught of extreme hot weather is of great importance.
The human body also is sensitive to the degree of hotness and coldness of the environment. This is the external temperature.
The make up of the body makes it very sensitive to extreme changes in temperature. This could lead to various malfunctions in the body. Therefore it is important that we do all possible to ensure we are protected during situations of extreme environmental temperature.
Some might like it hot, but extreme heat can overpower the human body. Climate change promises to bring with it longer, hotter summers to many places on the planet.
Heat exhaustion is a relatively common reaction to severe heat and can include symptoms such as dizziness, headache and fainting. It can usually be treated with rest, a cool environment and hydration (including refueling of electrolytes, which are necessary for muscle and other body functions). Heat stroke is more severe and requires medical attention—it is often accompanied by dry skin, a body temperature above 103 degrees Fahrenheit, confusion and sometimes unconsciousness. But when sustained heat waves hit a region, the other health ramifications can be serious, including sunstroke and even major organ damage due to heat.
How do humans cope with hot, hot weather?
The two ways we cope with heat are by
• perspiring and
So is it the heat or humidity that is the real killer?
The humidity is a huge factor. If you have tremendously high temperatures and high humidity, a person will be sweating but the sweat won’t be drying on the skin. That’s why it’s not just heat but the combination of heat and humidity that matters. That combination results in a number called the apparent temperature or “how it feels”.
Obviously there are thresholds for both temperature and humidity above which we see an increase in death.
The other major factor in terms of temperature that causes both mortality and morbidity is the temperature it falls to in the evening. If the temperature remains elevated overnight, that’s when we see the increase in deaths. The body becomes overwhelmed because it doesn’t get the respite that it needs. The effect of heat on our bodies varies with the relative humidity of the air. High temperatures with high humidity make it harder to lose excess body heat. This is due to the fact that when the moisture content of air goes up, it becomes increasingly more difficult for sweat to evaporate. The sweat stays on our skin and we feel clammy. As a result, we do not get the cooling effect of rapid evaporation.
While evaporative cooling is very effective in dry climates, there is a major drawback. That is the rapid loss of water and salts from the body through sweat. This can be fatal in less than a day if they are not replaced. It is common to lose a quart or more of water through sweating each hour in harsh summer desert conditions. Commercial “sport drinks” are designed to help people in these situations rehydrate and replenish lost mineral salts. It is easy and inexpensive to create your own equivalent drink without the unnecessary food coloring and sugar that the commercial drinks often include to make them more appealing to customers. Diluted lemonade with added salt can satisfactorily serve the same purpose.
Most people have the ability to physiologically acclimatise to hot conditions over a period of days to weeks. The salt concentration of sweat progressively decreases while the volume of sweat increases. Urine volume also reduces. In addition, vasodilation of peripheral blood vessels causes flushing, or reddening of the skin because more blood is close to the surface. That blood brings heat from the core body areas to the surface where it can be dissipated easily into the environment by radiation.
Hot weather and high humidity increase your risks by slowing the transfer of heat to the air around you. When you produce heat that raises internal temperature, your heart rate increases and vessels expand to bring more blood to the outer layers of skin, where the heat is released.
The body’s normal core temperature is 37-38C.
If it heats up to 39-40C, the brain tells the muscles to slow down and fatigue sets in.
At 40-41C, heat exhaustion is likely – and above 41C, the body starts to shut down.
Chemical processes start to be affected, the cells inside the body deteriorate and there is a risk of multiple organ failure.
The body cannot even sweat at this point because blood flow to the skin stops, making it feel cold and clammy.
Heatstroke – which can occur at any temperature over 40C – requires professional medical help and, if not treated immediately, chances of survival can be slim.
The best method of cooling people down is to immerse them in ice water or apply ice packs to the groin and armpits where crucial arteries are located – but it all depends on how long the body has been at an elevated temperature. Humidity – the amount of moisture in the air – is critical in determining how much we can sweat out.
Who is the most vulnerable to extended high temperatures?
We know the risk factors for dying from heat are urban dwellers who are elderly, isolated and don’t have access to air conditioning. Obese people are at increased risk as are people on certain medications. And people who are exercising or working in the heat, who don’t meet those criteria, can be at risk.
Some medications can make the body more susceptible to extreme heat:
A study showed that diuretics for high blood pressure and beta blockers—a number of studies showed that people taking them could be at increased risk.
There are some studies that have shown that certain mental health medications may impact a person’s ability to deal with the heat. But that’s a difficult one to get at. When you look at the number of people who die in a heat wave and the number of people who are taking those medications, the numbers can get pretty small pretty quickly.
Illnesses from excessive heat
Heat exposure causes the following illnesses:
• Heat edema is swelling which generally occurs among people who are not acclimatized to working in hot conditions. Swelling is often most noticeable in the ankles. Recovery occurs after a day or two in a cool environment.
• Heat rashes are tiny red spots on the skin which cause a prickling sensation during heat exposure. The spots are the result of inflammation caused when the ducts of sweat glands become plugged.
• Heat cramps are sharp pains in the muscles that may occur alone or be combined with one of the other heat stress disorders. The cause is salt imbalance resulting from the failure to replace salt lost with sweat. Cramps most often occur when people drink large amounts of water without sufficient salt (electrolyte) replacement.
• Heat exhaustion is caused by loss of body water and salt through excessive sweating. Signs and symptoms of heat exhaustion include: heavy sweating, weakness, dizziness, visual disturbances, intense thirst, nausea, headache, vomiting, diarrhea, muscle cramps, breathlessness, palpitations, tingling and numbness of the hands and feet. Recovery occurs after resting in a cool area and consuming cool drinks (e.g., water, clear juice, or a sports drink).
• Heat syncope is heat-induced dizziness and fainting induced by temporarily insufficient flow of blood to the brain while a person is standing. It occurs mostly among unacclimatized people. It is caused by the loss of body fluids through sweating, and by lowered blood pressure due to pooling of blood in the legs. Recovery is rapid after rest in a cool area.
• Heat stroke is the most serious type of heat illness. Signs of heat stroke include body temperature often greater than 41°C, and complete or partial loss of consciousness. Sweating is not a good sign of heat stress as there are two types of heat stroke – “classical” where there is little or no sweating (usually occurs in children, persons who are chronically ill, and the elderly), and “exertional” where body temperature rises because of strenuous exercise or work and sweating is usually present.
• Heat stroke requires immediate first aid and medical attention. Delayed treatment may result in death.
• What are symptoms and first aid steps for heat exhaustion?
• Symptoms of heat exhaustion may start suddenly, and include:
1. Nausea or irritability.
3. Muscle cramps or weakness.
4. Feeling faint.
8. Heavy sweating.
9. High body temperature.
First aid for heat exhaustion
1. Get medical aid. Stay with the person until help arrives.
2. Move to a cooler, shaded location.
3. Remove as many clothes as possible (including socks and shoes).
4. Apply cool, wet cloths or ice to head, face or neck. Spray with cool water.
5. Encourage the person to drink water, clear juice, or a sports drink.
What are the symptoms and first aid steps for heat stroke?
Heat exhaustion may quickly develop into heat stroke. Symptoms of heat stroke include:
• Hot, dry skin or profuse sweating.
• Loss of consciousness.
• Very high body temperature.
First aid for heat stroke includes
• Stay with the person until help arrives.
• Move to a cooler, shaded location.
• Remove as many clothes as possible (including socks and shoes).
• Wet the person’s skin and clothing with cool water.
• Apply cold, wet cloths or ice to head, face, neck, armpits, and groin.
Do not try to force the person to drink liquids.