Parts of the United States are currently in the grips of a blistering heatwave, with millions of people facing dangerously high temperatures.
In Tampa, Florida, the three-digit record was broken on Sunday, hitting 100 degrees Fahrenheit (37.7C).
The heat is only expected to intensify going into Monday, with a record 18 million people under a rare ‘extreme’ heat warning.
Some places in Mississippi and Louisiana could face temperatures as high as 120°F (49C).
Relief from the sweaty conditions is not expected for days, with people in Florida needing to wait until the weekend for cooler temperatures.
Hospitals and emergency rooms say they are ‘preparing for a potential influx of heat-related injuries’ as they warn of the dangers of heat stroke and heat exhaustion.
What happens to your body in a heatwave?
When exposed to intense heat,people can face increasingly severe illnesses such as severe dehydration, strokes and even blood clots.
The body has two primary mechanisms for maintaining its temperature.
The first is vasodilation, where the small blood vessels, or capillaries, just beneath the skin widen. This exposes more blood to the surface, where heat can be released through radiation.
A second mechanism is through sweating, which draws heat from the skin as it evaporates.
However, sweat contains salts, which are vital in muscle movement. This means if the body is sweating but the salts are not replaced, such as through a sports drink, the muscles can cramp.
These two actions help maintain the body’s internal temperature of 37 °C, a process known as thermoregulation.
However, as external temperatures exceed that level, it becomes harder for the systems to prevent the core temperature from climbing.
After heat cramps, the body may begin to suffer heat exhaustion. In addition to heavy sweating, early symptoms include feeling faint or dizzy. This is caused by an increased heart rate as more blood is pumped to the skin.
This can also lead to a weak, rapid pulse – for every 0.5C rise in core temperature, the heart rate goes up around ten beats per minute.
To prevent further heating, the brain tells the muscles to slow down, leading to a feeling of fatigue. Nausea and a headache may also set in.
At this point, anyone suffering these symptoms should stop all activity, rest, move to a cooler place and drink water or a sports drink.
If the body’s core temperature continues to rise above 40°C, the third and final illness to strike is heatstroke. This is the most severe form of heat stress and can be fatal.
The body’s heart rate will continue to increase, placing the organ under stress, while breathing may become rapid and shallow.
Skin may turn red as blood is pumped to the surface faster, but by this time, the body may be dehydrated and no longer producing sweat, reducing its capacity to cool down. Instead, skin may be hot and dry to the touch.
Heat stress risk factors
Age: Infants and children under four and adults over 65 are at a higher risk of heat exhaustion
Drugs:Some medications can affect the body’s ability to stay hydrated. These include beta blockers, diuretics, antihistamines, tranquilisers and antipsychotics. Some illegal drugs such as cocaine and amphetamines can also increase core temperature
Drinking alcohol: Alcohol can also affect the body’s ability to thermoregulate
Obesity: Excess weight can affect the body’s ability to regulate temperature
Sudden temperature changes: Those not acclimatised to hot temperatures will be more susceptible to heat-related illnesses
Source: Mayo Clinic
As heatstroke progresses it can lead to confusion, delirium, slurred speech and even seizures. The most severe cases can leave sufferers in a coma.
However, the first organ to begin to fail is usually the kidneys, which reduces the body’s ability to remove toxins from the blood, triggering failure in other organs.
If left untreated, heatstroke can be fatal – and as global temperatures rise, more people are going to be exposed to extremes.
A 2017 study published in Nature Climate Change projected that by 2100, 75% of the world’s population would be exposed to deadly heatwaves for at least 20 days of the year, compared to 33% today.
What is the hottest temperature ever recorded?
Death Valley in California is, as the name suggests, the hottest place on Earth.
Located in the Furnace Creek area in the California desert, it holds the record for the highest air temperature ever recorded.
It reached a staggering 56.7°C (134.1°F).
Average summer temperatures there often soar above 45°C (113°F).
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