Summer safety: Avoiding harm from heat

Most Canadian families welcome summer, and the chance to spend long, hot days outside. But as temperatures and humidity go up, so does the risk of heat-related illness. Parents are increasingly aware of some summer hazards, such as locking a child in a car. But many risks are harder to avoid.

If the body cannot shed enough heat for any reason, a child will suffer heat exhaustion and, in extreme cases, heat stroke — a medical emergency. Children are particularly vulnerable to heat-related illnesses, because their bodies do not get rid of heat as efficiently as adults' do. In the US, an average of 46 children under age 15 die each year from excessive heat, and a surprising number are in northern states with climates similar to southern Canada's. By watching for symptoms and knowing how to treat an overheating child, you can help ensure a safe, healthy summer.

About heat-related illness

Dehydration

Children can become dehydrated when they lose more body fluid by sweating or urinating than they replace by drinking. Even a small amount of dehydration, amounting to just 2% of body weight, can affect a child. Dehydration also increases the risk of other heat-related illnesses, because it interferes with the body's ability to regulate temperature.

Symptoms of dehydration include:

• dry or sticky mouth
• thirst
• low or no urine output; concentrated urine appears dark yellow
• not producing tears
• being irritable or cranky
• seeming bored or uninterested
• headache
• dizziness
• cramps
• chills
• fatigue

In severe cases, dehydration can cause:

• sunken eyes
• sunken soft spot, or fontanelle, on the top of the head in an infant
• nausea or vomiting
• lethargy or coma

If you suspect your child is dehydrated, move him to a cool, shady area and give him plenty of water, clear juice, or a sports drink. If he does not feel better soon, take him to see a doctor. If he is unconscious or unresponsive, do not wait; take him to see a doctor right away.

Hyponatremia

If a child drinks more water than he needs to replace lost fluid or if he loses large amounts of salt in sweat, this may cause a low blood sodium level, known as hyponatremia. You might suspect this condition if a child who has been sweating and drinking a lot of water becomes lethargic, confused or agitated, feels nauseous, has a headache, or experiences a seizure. Hyponatremia is quite rare but can be dangerous.

Hyponatremia is more likely to happen if a child:

• does not usually get enough salt in his diet
• loses large amounts of salt during strenuous or prolonged exercise
• drinks much more water than he needs during or after exercise

To prevent hyponatremia, it is important to replace both lost water and lost salt, either with a sports drink or a meal.

Heat cramps

Heat cramps usually happen during or after exercise when a child has lost large amounts of fluid and salt in sweat.

Symptoms of heat cramps include:

• intense muscle pain, which is not caused by injury, in the arms, legs, or abdomen
• muscle spasms that continue during or after exercise

If your child has heat cramps, he needs to stop exercising and sit down. Give your child clear juice or a sports drink to help replace fluid and salt. Light stretching, relaxation, and massage may also help. Make sure your child does not exercise for a few hours after the cramps stop.

If the cramps do not go away after an hour, take your child to a doctor.

Heat exhaustion

Heat exhaustion is caused by loss of water and salt, often as a result of exercise in hot weather. If it is not treated, it may progress to heat stroke.

Symptoms of heat exhaustion include:

• normal or elevated body temperature, although not as high as 40°C (104°F)
• profuse sweating
• pale skin
• skin may be cool and moist
• fast, shallow breathing
• fast, weak pulse
• headache
• nausea, vomiting, or diarrhea
• dizziness, weakness, or fainting
• heat cramps
• exhaustion

If your child has any of these symptoms, move him to a shady or air-conditioned area and have him lie comfortably. Remove extra clothing and sports equipment, if any. Cool him with cold water, fans, or cold towels. If he is not nauseated or vomiting, have him drink chilled water, juice, or a sports drink.

The child’s condition should improve quickly. If he does not seem better after an hour, take him to a doctor.

If his symptoms are severe, or if he seems confused or disoriented or is behaving oddly, take him to a doctor right away.

Heat stroke

Heat stroke is a dangerous illness that can lead to organ damage or death. Heat stroke happens when a child's body creates more heat than it can release. The child’s core body temperature increases rapidly, to 40°C or higher.

The main signs of heat stroke are:

• increase in core body temperature, usually above 40°C (104°F)
• central nervous system dysfunction, which may take the form of altered consciousness, seizures, confusion, emotional instability, or irrational behaviour

Other possible signs of heat stroke include:

• nausea, vomiting, or diarrhea
• headache
• dizziness or weakness
• hot and wet or dry skin
• increased heart rate
• fast breathing

Heat stroke is a medical emergency. Call 911/emergency medical services right away. Remove the child’s clothing and any sports equipment. Begin cooling the child by any means available, including immersing him in cold water, spraying him with cold water, fans, or ice bags. Monitor the child’s body temperature. Do not give the child anything to drink. If emergency services do not arrive quickly, call again for instructions.

Staying cool and preventing heat-related illness

Heat-related illness can be avoided by taking the right precautions. It helps to check your local weather forecast for heat and humidity warnings, and be aware of heat emergency alerts issued by Environment Canada.

In Canada, temperature and humidity readings are often combined into a humidex reading, a rough description of how hot it actually feels. While the humidex is not a perfect tool, you can use the humidex forecast for the day to plan ahead.

Humidex readings and comfort levels (Environment Canada)

If the humidex says it feels like:		You can expect:
Less than 29°C	Less than 84°F	No discomfort
30 to 39°C	85 to 102°F	Some discomfort
40 to 45°C	103 to 113°F	Great discomfort; avoid exertion
Above 45°C	above 113°F	Dangerous heat
Above 54°C	above 129°F	Heat stroke occurs quickly

To stay cool:

• Limit outdoor activities.
• Stay out of direct sunlight and crowded areas.
• Rest often in shady areas, or go to an air-conditioned space.
• Drink non-alcoholic fluids with no caffeine. Water is a good option, but children may drink more of a flavoured beverage such as juice or a sports drink.
• Avoid very cold drinks.
• Cool the body with water.
• Wear wide-brimmed hats and lightweight, light-coloured, loose-fitting clothing.
• Be aware that fans only move the air around; they do not cool it. Fans work best in front of an open window.
• Never leave children or pets alone in a car, even for a few minutes. On a sunny day, the temperature can shoot up by 30°C within 20 minutes. Cracking the window open will make very little difference.
• If your child is in a back seat restraint, put your briefcase or purse beside the car seat, or keep a teddy bear in the car to sit in the front seat and remind you. You may think you would never forget a child in a car, but it can happen to any parent.

Sports and exercise in the heat

Sports are an important part of summer for many children and teens. However, it’s important to avoid heat-related illness. Children who exercise in the heat are at higher risk than adults, because they produce more heat, sweat less, and may forget to drink enough.

If your child is going to be exercising or playing sports:

• Make sure the coach or supervisor is knowledgeable about exercising in the heat and that there is a plan for dealing with heat-related illnesses if they arise.
• Reduce the intensity of exercise when it is very hot, humid, or sunny.
• Take frequent breaks. Plan a rest in the hottest part of the day.
• Wear lightweight, light-coloured, loose-fitting clothing.
• A helmet makes it harder for the body to get rid of heat, which means slowing down and taking breaks. It does not mean it's OK to take off the helmet.
• Make sure children are well hydrated before exercising.
• Make sure children drink every 15 to 20 minutes when exercising, even if they don’t feel thirsty. One way to tell whether your child is drinking enough is to weigh him before and after the activity, wearing very little clothing. If he weighs less after the activity than before, he is not drinking enough. However, if he weighs more after the activity, he is drinking too much.
• Don’t use salt tablets to replace electrolytes. They provide too much salt.
• If it is very hot and humid, cancel the activity or move to an air-conditioned space.
• Remember that these tips apply to informal activities too, such as hiking, cycling, or skateboarding. You might suggest swimming instead. Make sure teens are aware that heat stroke can do serious harm to the organs and brain.

The World Health Organization predicts that heat-related illness and deaths will increase worldwide in the coming decades due to climate change. Canadian experts warn that we may be less prepared than many other countries, partly due to our historical focus on cold weather hazards. But by paying closer attention to children on hot days, we can keep them safe even in a warming world.

Resources:

Environment Canada Weather Warnings:
http://www.weatheroffice.gc.ca/warnings/warnings_e.html

US Centres for Disease Control and Prevention resources for extreme heat:
http://www.bt.cdc.gov/disasters/extremeheat/