
from Health & Safety Watch - Health through Knowledge - July 20, 2011 ... With several heat advisories being issued in many parts Canada this summer, it is a good idea for all Canadians to remind themselves about the risks associated with excessive heat and ways to stay safe. The following general information was adapted from various sources. For more specific information for your area, including cooling centres if they exist, please consult with your local public health authorities.
Extreme Heat Events
During extreme heat events 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: high air temperature, high air moisture content (often expressed as relative humidity), radiant (sun) load, and lack of air movement (wind - which usually moderates the negative effects of the other factors).
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: radiation (you send out infra-red rays to your surroundings), convection (you transfer heat directly from your skin to the air), evaporation (of sweat) - in high heat, this is particularly important. Your heart must be effectively pumping blood to your extremities (head, hands and feet) in order for these three things to happen.
Recommended Actions:
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. 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:
•Keep out of the sun. If your house is cooler than outdoors, stay inside.
•If you must go outdoors into the sun, shade yourself with an umbrella or a wide-brimmed hat with lots of ventilation (to allow the sweat on your head to evaporate).
•Drink lots of water (that's the best liquid). How much water you should drink depends on how much you're sweating. It might just be a cup or two an hour, or it may be several litres. Thirstiness is not a good gauge. It doesn't kick in until you've already lost enough water to contribute to heat strain.
•If it is sunny, keep your house cooler, by pulling down awnings or closing outdoor shutters (if you have them) over your windows, or keep the curtains/blinds closed.
•If you have a two-storey house, keep the upper-level windows slightly open, to draw excess heat up and out.
•If your house is hot, try to spend a few hours in an air-conditioned space, such as a mall, or a formal cooling centre. In any case, make sure to rest in cool shade periodically.
•Take a cool bath or shower.
•At night, if the outdoor temperature is cooler, open all your windows. If you have fan units that fit into the windows, use them to bring down the temperature faster.
•Use fans to evaporate sweat from your body and cool it. If the temperature and humidity are both very high, this may not be effective or may have the opposite effect.
•Limit your physical activity, especially if you are in an at-risk group, and certainly during the middle of the day, when the heat is greatest.
•Liquids that are high in sugar and/or alcohol should be avoided, as they can increase the amount of water lost by the body.
•Most people's diets contain enough salt to make up for losses in sweat. But if you experience heat cramps, are advised by your doctor, or have to work in the heat and are sweating a lot you may want to take in extra salt.
•If you take medication, check with your doctor or pharmacist for possible side effects during extreme heat.
•Offer to help and check up on your neighbours, especially those who may be on their own and who may not be in a position to take these precautions.
•Heat should not be your only concern. If you are going outdoors in the daytime, apply sunscreen (to limit ultra-violet ray exposures). If you are going out at dawn or dusk (when mosquitos are most active) remember to apply insect repellant.
Get help from a friend, relative or doctor if you have these symptoms of heat illness:
•Rapid breathing or difficulty breathing
•Weakness, dizziness or fainting
•More tiredness than usual
•Headache
•Confusion
•Nausea
Make use of local cooling centres:
In addition to using air conditioned public places such as shopping malls, local libraries and neighbourhood community centres as places to cool off, many cities have Cooling Centres that are open during Extreme Heat Alerts. Check with your local authorities.
Don't forget about your pet!
Without shade and water, dogs, cats and other pets can overheat, become ill and die within a short time. Summer is when pets have the greatest risk of injury and heat-related health problems. Here are some tips to keep them cool.
•Watch for signs of heat stroke: Signs include rapid panting, lots of drooling, hot skin, twitching muscles, vomiting and a dazed look. Act quickly to cool down your pet - wrap it in a towel soaked with cool (not cold) water, or place it in a bathtub with cool water, or pour cool water over the pet. You can also put ice packs on the animal's head. Consult your veterinarian if your pet has heat stroke.
•Provide plenty of fresh water: Dogs can only sweat by panting or through the pads of their feet. Water loss from the wet surfaces of their mouth and nose helps lower their body temperature. Pets need fresh water at home and outdoors, so take water with you for your pet.
•Watch out for sunburn! Watch out for hot pavement and beaches: Sensitive paws burn easily. Water, sand and rock, at the beach reflect sunlight - your pet could get sunburn. Short hair pets and those with pink skin or white hair are most likely to burn. Control your pet's exposure to the sun - limit the time and provide shade.
•Find a cool spot: Keep air circulating indoors for pets - use a fan or air-conditioning. Provide shade outdoors for pets. A gentle sprinkle from a garden hose is also helpful to keep them cool.
•Watch how much pets eat and exercise: Overeating during hot weather can lead to overheating, so let your pets eat less. Also avoid exercise or vigorous activity during the hottest part of the day.
•Never leave your pet in a parked car! Even with the window open slightly or parked in the shade, when the temperature outside reaches 30°C the temperature inside a car can reach 50°C in minutes. This is extremely dangerous to your pet. Although your pet may want to come with you, it is much kinder to leave it at home with plenty of fresh cool water and shade. Carry a spare key with you to avoid locking your pet accidentally in your car.