Although the human body is well adapted to maintaining a stable body temperature of around 37C, a run of hot days, known as a heatwave or extreme heat event, threatens its ability to cope.

Heat stress, including heat exhaustion and heat stroke, occurs when the body’s temperature regulating centre is no longer able to cope with heat generated by both the body and the environment.

With heat exhaustion, excessive sweating in a hot environment reduces the blood volume. Warning signs may include paleness and sweating, rapid heart rate, muscle cramps, headache, nausea and vomiting, dizziness or fainting.

With heat stroke, the core body temperature rises above 40.5C and the body’s internal systems can start to shut down. This can result in delirium, coma and seizures and can cause damage to the liver, kidney, muscles and heart.

Worrying signs to look out for - increased heart rate, nausea and vomiting, dizziness and feeling faint, confusion, headaches, muscle cramps and weakness and urinating less often.

Life threatening signs may include - seizures, reduced level of consciousness, dry, red, hot skin.

What to do
Call an ambulance on 000 if there are life-threatening signs.
If not life threatening, rest in a cool well-ventilated area.
Drink plenty of fluid (consider clear juice or low-sugar sports drinks).
Apply cool wet cloths to skin.
Seek medical advice if your condition does not improve.

Call Healthdirect Australia: 1800 022 222, contact your GP or attend the local emergency department.

Keep safe: protect your body from the heat
Drink plenty of fluid (not caffeinated, energy or alcoholic drinks).
Find a cool place, in the shade or in a well-ventilated shelter with fans or air-conditioning.
Cool down periodically in water (swimming pool, bath or shower).
Wear lightweight, light-colour, loose fitting clothing and head protection. Remember “Slip, Slop, Slap”.
Apply effective sunscreen (SPF 30+).
Limit physical activity and avoid exercising in the heat of the day.

Monitor the colour of your urine (dark yellow is bad, clear urine is good).

In a heatwave
Use your air-conditioner or a fan if you have one.
Place a bowl of ice cubes in front of an electric fan for a cooling breeze.
Avoid going out in the hottest parts of the day.
Rest and take naps in a cool darkened room.
Use a spray bottle filled with water to cool your face and body.
Place a wet face-flannel or towel on your head or neck.
Intermittently have a cool shower or bath, or place your feet in a bowl of cold water.

Sleep with just a sheet over you and wear few night clothes.

What is a heatwave?

A period of abnormally and uncomfortably hot weather, which could affect human health, community infrastructure and services.

Not defined on the basis of temperature alone, the factors that contribute to a heatwave are the maximum day temperature and the minimum night temperature, the duration of the high temperatures, humidity and air quality and the availability of cooling facilities and power to operate the cooling facilities and urban and rural design.

The heatwave threshold for the Perth metropolitan area is a mean temperature of 32C or greater for one or more days. The mean temperature is the average of the forecast daily maximum temperature and overnight minimum temperature (e.g. max 40C, min 25C)

Source: public.health.wa.gov.au.