It's Your Health
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Many regions of Canada are experiencing more frequent, more severe and/or longer extreme heat events, sometimes called "heat waves". It is important to take precautions to protect your health.
During extreme heat events (as announced by Environment Canada, or your local municipality/ Health Unit) the weather changes rapidly, leading to high temperature and/or humidity that your body may not be adjusted to. This is made worse if you are in the sun, or if there is little to no wind. During these extreme heat events there is typically a lack of night-time cooling and air quality is often poor.
Four environmental factors work together to make it hot enough to put health at risk.
Even at rest your body generates heat. In the summer time it is important to constantly release this heat from your body. For your body to function properly, its inner (core) temperature should be close to 37°C. This normally varies by a few degrees over the course of the day and during physical activity. As your work load and body heat increases, so does the need to lose that heat. A core temperature of 40 or 41°C is considered life-threatening if you don't have a fever. If you are sick with an infection you may have a fever, this is not necessarily life threatening as it is the body's way of fighting off the infection.
You maintain your core body temperature by giving off heat through a combination of:
Your heart must be effectively pumping blood to your extremities (head, hands and feet) in order for these three things to happen.
Heat strain can result in several heat related illnesses. Some of these are direct effects, and include:
A heat stroke (or sun stroke) is a true medical emergency. Dial 911 immediately. During heat stroke the victim will have a body temperature that is above 40-41 °C, but they will have stopped sweating. They may also have:
The longer a person's body temperature is above 40°C, the greater the likelihood that he/she will suffer permanent effects, or death. While waiting for the ambulance, sponge him/her down with cool water.
Exposure to heat can also cause health problems indirectly, such as through the increased work load on the heart. In extreme heat, your heart has to pump harder to get blood to your extremities, even when you are at rest, and may be pushed over its limits.
If you have a pre-existing medical condition, you need to be particularly careful, as you may be more susceptible to the effects of an extreme heat event. For example, if your heart does not work at full capacity, if you use certain drugs, or even if you are dehydrated, you may be at an increased risk.
During extreme heat, the most important thing is to keep cool and not expose yourself to heat stresses that will put a strain on your body.
You can keep cool in a number of ways, bearing in mind the four environmental factors of heat stress given in the Background section. At elevated temperatures, virtually all of your heat loss occurs through evaporation of perspiration (sweat) from your body. Anything that increases the rate of evaporation of sweat, such as personal cooling fans, is helpful.
You can also prepare your body for exposure to high heat by acclimatizing it. If you expose yourself to heat in a controlled way, for a few hours a day, then during the span of a week, your body can adjust. Of course, if you spend all of your time in an air-conditioned environment, your body will not adjust to heat.
To help protect yourself during an extreme heat event, take these steps:
Health Canada and the Public Health Agency of Canada are committed to maintaining and improving the health of Canadians. We are working with our partners to better understand the impacts of extreme heat on the health of Canadians, particularly those at greatest risk, and to promote efforts to reduce these risks. We provide information to Canadians on steps they can take to maintain and improve their health, including information on how they can prepare themselves to adapt to prolonged periods of extreme heat.
For more information, visit the following Government of Canada Web sites:
Health Canada, Climate Change and Health Web section
Or e-mail us at: climatinfo@hc-sc.gc.ca
For
weather conditions in your area
For more information on summer health and safety issues go to:
Health Canada, Healthy Living, Safe Summer Fun
Health Canada, It's Your Health, Summer Information section
For additional articles on health and safety issues go to the It's Your Health Web section.
You can also call us toll free at 1-866-225-0709 or TTY at 1-800-267-1245*
Updated: July 2009
Original: October 2006
İHer Majesty the Queen in Right of Canada, represented by the Minister of Health, 2009