Hot days are ahead! We love warm weather but those who are not so used to the heat should be careful. Young children, the elderly, those with chronic illnesses, and those taking medications are especially susceptible to the bad effects of extended sun exposure.

Heat-related illnesses

Despite some restrictions, we’ll be spending a lot of time outdoors. While enjoying your summer activities, remember that too much heat can be harmful to your health. Heat exhaustion can start with a dull, throbbing headache which can lead to nausea and fainting. Other symptoms of heat-related illness are:

• Pale, cool, moist skin
• Heavy sweating
• Rapid shallow breathing
• Fatigue and weakness
• Dizziness
• Swelling (especially hands and feet)
• Irritable, bizarre or aggressive behavior

Move to a cooler place immediately and drink water when you feel these symptoms. Heat exhaustion or stress is a milder stage of heat-illness. If unchecked, it can lead to more severe conditions such as:

Heat rash – This is skin irritation caused by sweat that does not evaporate from the skin. Also called prickly heat, heat rash is the most common problem in hot work environments.

Heat cramps – Painful cramps are caused by loss of body salts and fluid during sweating. Low salt levels in muscles cause cramping in the legs or arms.

Heat stroke or sunstroke – This happens when the body fails to regulate its own temperature and it rises often to 40.6 °C. Someone suffering from heatstroke can have a fever (core body temperature of 40°C or more); hallucinations; red, hot, dry skin (in the late stages of heatstroke); seizures; and unconsciousness/coma. A heatstroke is life-threatening; it is considered a medical emergency. Call 911 immediately when you notice these symptoms.

Preventing heat-related illness

1. Avoid staying outside during the hottest part of the day

   As much as possible, stay indoors between 10 am until 4 pm, or at least limit your activity under the sun during this period. Find a shady spot or bring an umbrella if you have to be outdoors.

2. Always wear sunscreen

   Apply sunscreen with SPF 15 or higher before leaving the house. Keep the sunscreen tube with you because you may sweat it off as the day goes on (or wash it off if you are going swimming). Look for broad-spectrum sunscreen as it will protect you from UVA and UVB rays.

3. Know the humidex rating

   The humidex rating tells you how the current weather will feel to an average person (it’s like the wind chill factor but for summer). Here’s a guide:

   • Humidex range 20-29°C – comfortable
   • 30-39°C – some discomfort
   • 40-45°C – great discomfort; avoid exertion
   • Above 45°C – dangerous; heat stroke possible

   Knowing the humidity factor helps you predict how well your body can cool itself. As the CCOHS explains it: “The body attempts to maintain a constant internal temperature of about 37°C at all times. In hot weather, the body produces sweat, which cools the body as it evaporates. As the humidity or moisture content in the air increases, sweat does not evaporate as readily. Sweat evaporation stops entirely when the relative humidity reaches about 90 percent. Under these circumstances, the body temperature rises and may cause illness.” To calculate the humidex rating, you’ll need to know the air temperature and the dew point.

4. Drink water

   Always have a water bottle with you and drink enough water. Drinking a litre for each hour is recommended if you are playing sports, dancing (attending a festival for example) or working under the sun. Taking food and drinks high in electrolytes such as sodium and potassium can also help (samples of these types of food: Staying hydrated: Electrolytes 101). Avoid alcoholic or caffeinated drinks because they are diuretics (promotes urination). This takes away more fluids from your body making you more prone to heat injury.

5. Wear lightweight, light-coloured, loose-fitting clothing

   Wear fabrics that allow the air to circulate and the heat escape. Choose light-coloured clothes since they reflect light while dark colours absorb it. Add a wide-brimmed hat when outdoors to protect your hair, ears, eyes, neck and skin from the sun’s rays.

6. Take frequent breaks

   Take a lot of breaks in a cool area if you’re working, playing or exercising outdoors. Rest, drink water and keep cool before you go out again.

7. Be mindful of symptoms

   If you are starting to feel dizzy from the heat, seek shade immediately or go to an air-conditioned area. Take plenty of rest and stay hydrated. Ask for help if symptoms persist or worsen.

8. NEVER leave kids, seniors and pets in the car

   Even if you crack the windows open a bit, the temperature will tend to be hotter inside the car under the sun. The heat can get deadly even for just a few minutes.

 
Article updated July 5, 2021.
 
Sources: Heat-related emergencies: Staying cool and hydrated in Canadian summers, Canadian Red Cross; Heat-related illness, HealthLink BC; OSH Answers Fact Sheets, Canadian Centre for Occupational Health and Safety; and ‘A litre an hour’: Tips for surviving Manitoba summer heat, Sharon Pfeifer and Nikki Jhutti, Global News. All retrieved July 19, 2018.