With weekly forecasts of mid 20s to 30s in the next few weeks, Manitobans are in for a hot summer. While we love to bask in the sunshine, those who are not so used to the heat can be in danger if they’re not careful. Young children, the elderly, those with chronic illnesses and those taking medications are especially susceptible to the ill effects of extended sun exposure.
With so many summer festivals, fairs, and outdoor markets lined up, a lot of us will be spending time outdoors. While you’re enjoying all these summer activities, it will be good to be mindful that too much heat can be harmful to your health. Heat exhaustion can start with a dull, throbbing headache, leading to nausea and fainting. Other symptoms of heat-related illness are:
- Pale, cool, moist skin
- Heavy sweating
- Rapid shallow breathing
- Fatigue and weakness
- Swelling (especially hands and feet)
- Irritable, bizarre or aggressive behavior
When you notice these symptoms, move to a cooler place immediately and start hydrating. 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 painful cramps in the legs or arms.
Heat stroke or sunstroke – This is life threatening and considered a medical emergency. This happens when the body fails to regulate its own temperature and body temperature continues to rise, often to 40.6 °C. A person suffering from heat stroke can have fever (core body temperature of 40°C or more); hallucinations; red, hot, dry skin (in the late stages of heat stroke), seizures and unconsciousness/coma. Call 911 immediately.
Preventing heat-related illness
- Avoid staying outside during the hottest part of the day – If you can avoid it, stay indoors between 10 am until 4 pm, or at least limit your activity under the sun during this period. If you need to be outdoors, find a shady spot or bring an umbrella.
- Know the humidex rating – The humidex rating tells you how the current hot and humid weather will feel to an average person (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
It is important to know the humidity factor because it can 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 per cent. Under these circumstances, the body temperature rises and may cause illness (Humidex rating and work, Canadian Centre for Occupational Health and Safety).
- Drink enough water – Always have a filled water bottle handy and drink enough water. If you are attending a festival for instance, Manitoba’s medical officer of health, Richard Rusk, recommends drinking a litre for each hour. Taking food and drinks high in electrolytes such as sodium and potassium can also help (see this article for samples of these types of food: Staying hydrated: Electrolytes 101). Don’t drink alcoholic or caffeinated beverages because they are diuretics (promotes urination). This takes away more fluids in your body making you more prone to heat injury.
- Wear lightweight, light-coloured, loose-fitting clothing – Light-colours reflect light while dark colours absorb it making it more practical to wear light clothing if you want to stay cool. Choose clothes that allow the air to circulate and the heat escape. Also, wear a wide-brimmed hat outdoors to protect your hair, ears, eyes, neck and skin from the sun’s rays.
- Always wear sunscreen – Apply sunscreen with SPF 15 or higher before leaving the house. Keep the sunscreen bottle with you because you may sweat it out as the day goes on (or wash it off if you are going swimming) so you may need to re-apply it. Look for broad-spectrum sunscreen as it will protect you from UVA and UVB rays.
- 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 under the sun.
- Be mindful of the 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.
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.
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