How does heat stress affect the body and how to cope in a heatwave

A woman uses a hat to shield her face from the sun in Trafalgar Square during the hot weather in London, on July 18, 2022. PHOTO: REUTERS

LONDON (AFP, REUTERS, NYTIMES) - Europe is in the grip of a record-breaking heatwave and wildfires are raging across the Mediterranean. Searing summer heat waves are also expected to return this week across large parts of China, lasting through late August, the state weather forecaster said, despite brief interludes of seasonal rain.

When the body is exposed to unusually high temperatures, it can have the following effects:


• Increased heart rate

• Fall in blood pressure

• Increased risk of cardiac arrest

Blood circulation

• Formation of blood clots

• Alteration of oxygenated blood flow to vital organs


• Excessive sweating

• Failure of sweating mechanism in extreme heat

• Skin feels hot to the touch

Nervous system

• Headaches

• Faintness, dizziness

• Confusion, reduced awareness

• Convulsions

Renal system

• Disruption of blood flow and oxygen to the kidneys

• Low production of urine

• Kidney dysfunction

Digestive system

• Nausea, vomiting

• Damage to the intestines


• Impaired function

• Cramps due to dehydration

• Spasms

How to cope in a heatwave

People cool off in a water fountain during a heatwave, at Trafalgar Square in London, on July 19, 2022. PHOTO: REUTERS


To reduce the risk of heat stroke, here is what seniors can do:

• Shade your rooms from the heat

• Avoid going out during the hottest hours of the day

• Moisten your skin regularly

• Spend several hours in a cool or air-conditioned room

• Eat more fruit, vegetables and cold food

Children and adults

To reduce the risk of dehydration, here is what children and adults can do:

• Do not stay out in the full sun

• Drink lots of water and avoid alcohol

• Avoid intense physical effort

Heat-related illnesses

Sign is displayed in Dovedale during the heatwave, Derbyshire, Britain, on July 19, 2022. PHOTO: REUTERS

Here is a look at the most common health effects or symptoms caused by extreme heat:

Heat cramps

Main symptoms

Painful muscle cramps or spasms (abdomen, arms, calves), heavy sweating.


Prolonged exposure to extreme heat, combined with dehydration.

Immediate treatment

• Stop activity

• Move to a cooler location

• Drink non-alcoholic fluids

• Seek medical attention if cramps persist

Heat exhaustion

Main symptoms

Heavy sweating, fatigue, dizziness, nausea or vomiting, thirst, fainting, headache, irritability.


Exposure to extreme heat over extended period (usually several days), combined with dehydration. It is a severe illness that requires emergency medical treatment.

Immediate treatment

• Move to cool/air-conditioned environment, use wet cloth or cold packs to cool down

• Sip non-alcoholic fluids

• Loosen clothing

• Seek medical attention if symptoms worsen or persist, or if person has heart problems or high blood pressure

Heat stroke

Main symptoms

High temperatures, profuse sweating, fast heart rate, severe vomiting or diarrhoea, hot/flushed skin, unconsciousness, difficulty breathing, altered mental state.


Prolonged exposure to, or physical exertion in, high temperatures. Body fails to regulate its temperature, 40 deg C or higher.

It is the most serious medical condition that requires emergency treatment. It can result in death.

Immediate treatment

• Seek emergency help

• Reduce body temperature with available resources (wet blanket, ice packs, cool bath, water spray)

• Move person to cooler place, no direct sunlight

• Remove unnecessary clothing

• Watch for signs of progressive heat stroke like unconsciousness or difficulty in breathing. Cardiopulmonary resuscitation, administered by a trained person, may be required


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