Outdoor Air Quality

Smog is a mixture of air pollutants, primarily originating from vehicle emissions and industrial pollutants. The air quality health index (AQHI) and air quality alerts provide you with information about local air quality and advice on how to protect your health.

Poor air quality can have negative health impacts, particularly on your heart and lungs, and may worsen many chronic diseases. Some people are more vulnerable to smog including young children, the elderly, outdoor workers, sports enthusiasts, and people with chronic conditions, including heart disease, chronic bronchitis, emphysema, and asthma. 

The Air Quality Health Index (AQHI) is a scale designed to help you understand what the quality of the air around you means to your health. The AQHI is a number from 1 to 10. The higher the number, the greater the health risk.

Air Quality Health Index

When a high AQHI is forecasted, Environment Canada will issue a smog and air health advisory. You can sign up to receive smog advisories and other air quality alerts.

To reduce your exposure to smog and its potential health effects:

  • Check the AQHI forecast daily, especially during “smog season” from April to September.
  • Sign up to receive smog and other air quality alerts.
  • Avoid or reduce strenuous outdoor activities when smog levels are high, especially during the afternoon when ground-level ozone reaches its peak. Choose indoor activities instead.
  • If you have a heart or lung condition, talk to your healthcare professional about additional ways to protect your health when smog levels are high.

Wildfire smoke, air quality and health

Smoke from wildfires can be a major source of air pollution. Wildfire smoke may be carried hundreds or thousands of kilometres from the fire. Air quality due to wildfire smoke can fluctuate over short distances and can vary considerably from hour to hour. It is important to monitor air quality statements in your area so you can prepare to respond to changing conditions.

Learn how to check the local air quality conditions. Pay attention to:

There are precautions you can take to reduce exposure to wildfire smoke, including:

  • Limiting outdoor activities and strenuous physical activities
  • Look for breaks in the smoke to find opportunities to go outdoors
  • Set HVAC systems to recirculation mode when the outdoor air quality is poor, and bring in fresh air when the outdoor air has improved
  • Protect indoor air quality by keeping windows closed when the temperature is comfortable

Learn more about how to protect yourself from wildfire smoke: