Air quality in Ontario

What is air quality

Air quality describes the state of the air around us. Good air quality means clean, unpolluted air.

Poor air quality happens when pollutants reach concentrations that are of concern to human health and/or the environment.

Poor air quality comes from a number of factors, including emissions from various natural and man-made sources (e.g. forest fires, vehicles, power plants, industrial processes and residences), and is influenced by  atmospheric and weather conditions.

Air pollution and your health

Clean air is critical for human health and the health of the environment.

Air pollution can:

• make it harder to breathe
• irritate your lungs and airways
• worsen chronic diseases such as heart disease, chronic bronchitis, emphysema and asthma

Each person reacts differently to air pollution. Children, seniors and those with diabetes, heart or lung disease are most sensitive to the effects of air pollution.

Negative health effects can increase as air pollution worsens. Symptoms can increase if you are exposed to air pollution for a long time or breathe in a lot of it.

Monitoring air quality

Ontario has a network of 38 ambient (outside) air monitoring stations across the province that collect air pollution data and report information on key pollutants that are indicators of overall outdoor air quality.

This information is shared with the public through our Air Quality Health Index (AQHI) hourly. The Air Quality Health Index represents the relative risk of a mixture of common air pollutants that are known to harm human health.

We provide AQHI readings and forecasts, air pollution data, as well as information on what to do when a Special Air Quality Statement or Smog and Air Health Advisory is issued.

We publish an annual air quality report that provides information about the state of air quality provincewide and examines 10-year trends for key pollutants.

Status of our air quality

Our air quality has improved significantly over the past 10 years.

Since 2007, levels of smog-causing pollutants in the air have declined significantly:

• 53% decrease in carbon monoxide
• 51% decrease in sulphur dioxide
• 30% decrease in nitrogen dioxide
• 12% decrease in fine particulate matter

In 2016, Ontario’s air was rated very good or good for 93% of the year and there was one smog advisory.

Improving and protecting air quality

To improve air quality and help fight climate change, we:

• have eliminated coal-fired power plants
• have implemented Drive Clean vehicle emissions testing
• are placing emissions caps on sulphur dioxide and nitrogen oxides
• continue to develop new air standards and rules for industrial air emissions including:
  • new rules to regulate industrial sources of air pollution for petroleum and petrochemical industries
  • new rules for regulating air contaminants for the metal finishers and foundries sectors
  • creating provincial air zones that will help direct government actions to maintain and improve air quality based on the unique circumstances of each area of the province
  • more stringent sulphur dioxide air standards, a by-product of fossil fuel combustion and industrial smelting processes.