The air outside plays an important role in lung health—especially for people living with chronic lung conditions. Because outdoor air quality can shift from hour to hour depending on weather, pollution, and seasonal changes, staying informed can make a real difference. Here, you’ll find what affects air quality, how to read common air quality indicators, and practical tips to help protect your lungs all year long.
Air Quality Health Index (AQHI)
The Air Quality Health Index (AQHI) is a tool used across Canada to help people understand how outdoor air pollution may affect their health. It reports risk levels on a scale from 1 (low risk) to 10+ (very high risk) and provides health guidance for the general population and for those at higher risk.
From the Government of Canada website:
Health Risk | Air Quality Health Index | Health Messages | |
At Risk Population* | General Population | ||
Low | 1 – 3 | Enjoy your usual outdoor activities. | Ideal air quality for outdoor activities. |
Moderate | 4 – 6 | Consider reducing or rescheduling strenuous activities outdoors if you are experiencing symptoms. | No need to modify your usual outdoor activities unless you experience symptoms such as coughing and throat irritation. |
High | 7 – 10 | Reduce or reschedule strenuous activities outdoors. Children and the elderly should also take it easy. | Consider reducing or rescheduling strenuous activities outdoors if you experience symptoms such as coughing and throat irritation. |
Very High | Above | Avoid strenuous activities outdoors. Children and the elderly should also avoid outdoor physical exertion. | Reduce or reschedule strenuous activities outdoors, especially if you experience symptoms such as coughing and throat irritation. |
The bottom line? Wildfire smoke is bad news for breathing, but there are steps you can take to lower your risk of lung condition flare-ups.
Climate Change
Climate change is closely linked to worsening air quality. Rising temperatures, changing weather patterns, and more frequent extreme events can increase pollution levels and lengthen allergy seasons.
How climate change affects air quality:
- An increase in air pollution levels—pollutants such as ozone and particles of different sizes (particulate matter, or PM),
- More frequent or severe air pollution and heat episodes—which together, have an even greater impact
- Increased emissions from the natural environment—such as from fires and dust.
- Increase in aeroallergen levels—substances in the air, like pollen, that can cause allergic reactions
What this means for lung health
People with respiratory conditions may experience more frequent symptoms, flare-ups, or reduced lung function during periods of poor air quality. Monitoring conditions and planning ahead can help reduce risk.
For official information, visit Climate Change and Public Health Factsheets.
Seasonal Pollen & Allergies
Each spring and summer in Canada brings elevated amounts of airborne pollen from trees, grasses, and weeds that can irritate the respiratory system and trigger allergy symptoms such as sneezing, itchy eyes, and nasal congestion. People with asthma or other lung conditions may find their symptoms worsen when outdoor aeroallergens are high.
Find out how pollen and environmental changes may affect your symptoms. See trusted information and prevention tips: Climate Change and Public Health Factsheets.
Temperature Inversions (Winter)
Think air quality is a summer issue? Think again! In winter, temperature inversions can trap air pollutants, including fine particulate matter and other gases, close to the ground, leading to poor outdoor air quality that affects lung health.
Understand how winter weather can trap pollution near the ground. Read how weather patterns affect air quality: Air quality model and weather.
Wildfire Smoke
Wildfire smoke can travel hundreds or even thousands of kilometres and significantly reduce air quality. If you want to learn how to prepare for smoke events, reduce exposure, and protect your lungs, visit our dedicated resource page.
More information can be found on the Health Canada resource page on wildfire safety: Wildfire smoke and your health
