Outdoor Exercise During Heat and Smog Alerts

Often high air pollution occurs during hot weather conditions. People with heart and lung conditions, seniors and children should pay special attention to the hourly Air Quality Health Index levels and forecasts.

Exercising outdoors during a heat or smog alert?

High smog and heat levels can be dangerous to health. Toronto Public Health estimates that because of air pollution, every year about 1,700 people die earlier than expected and 6,000 visits are made to hospital because of heart and lung diseases.

A Smog Alert is called when smog conditions reach dangerous levels. Most of Toronto's smog comes from the burning of fossil fuels to run motor vehicles and generate electricity.

A Heat Alert is called when the combination of heat, humidity and other weather conditions can be very dangerous.

During high smog or heat levels, health risks may increase for:

  • Those who play sports or exercise outdoors
  • Cyclists
  • Others who are active outside (e.g. gardeners)

Parents, coaches and others supervising children should be aware of the health risks during a Smog or Heat Alert.

How air pollution and heat affect your body

When you exercise or do hard physical work in polluted air, you breathe harder than normal and bring dirty air deeper into your lungs. You also breathe through your mouth, bypassing the filtering action of your nose. If you exercise when it is very hot, your body temperature gets very high and your body has to work extra hard to keep cool.

When exercising outdoors during a Smog Alert, even healthy people may:

  • Cough or sneeze
  • Feel irritation in the throat
  • Have difficulty breathing
  • Inflame and damage lung cells (short and long term)
  • Reduce the body's ability to fight off respiratory infections
  • Have difficulty performing their best (the lungs can't work at full capacity)

If you exercise outdoors during a Heat Alert,you may:

  • Get heat cramps – muscle pains in the legs, arms or abdomen
  • Have a very high body temperature that could damage vital organs
  • Suffer from headache, nausea, dizziness, confusion and/or weakness due to heat-related illness

If you have a lung or heart problem, exercising outdoors during a Smog or Heat Alert could make your problem worse.

Protect your health during Heat and Smog Alerts

Reschedule sports practices and outdoor exercise to another time, when the smog or Heat Alert is over. Or exercise indoors in an air conditioned area.

If you're going to be active outdoors:

  • Drink plenty of water before, during and after exercise
  • During exercise, drink water every 15-20 minutes
  • Wear loose-fitting clothes that allow sweat to evapourate
  • Wear a hat and use sunscreen, at least SPF 15
  • Take lots of rest breaks, preferably in the shade or an air conditioned area
  • Exercise or play sports in shaded areas
  • If you jog or cycle, stay away from busy streets especially during rush hours

Stop exercising and seek medical help if you have the following symptoms of illness:

  • Difficulty breathing
  • Weakness or fainting
  • More tired than usual
  • Nausea
  • Headache
  • Confusion

You can help a sick person by doing the following:

  • Call for help
  • Remove excess clothing from the person
  • Cool the person down by patting or sponging with cool water
  • Move the person to a cooler place
  • Give the person sips of cool water (not ice water) or sports drink

Last updated May 2011