Frequently Asked Questions


Is Ontario's air quality getting better or worse?

Ontario's air quality has improved steadily since 1988. We have good air quality approximately 90 per cent of the time.


Where is the best air quality and lowest incidences of smog in the province?

Generally, air quality improves as you travel northward and eastward across the province, however, the formation and transport of smog is strongly dependent on meteorological conditions. 

Summer smog episodes in Ontario are often a part of a regional weather condition that prevails over much of northeastern North America.  Elevated levels of ozone and fine particulate matter are typically due to weather patterns that affect the lower Great Lakes region.  Such weather patterns are invariably associated with slow-moving high pressure cells across the region and result in the long-range transport of smog pollutants from neighbouring U.S. industrial and urbanized states during the flow of warm air from the southwest to the northeast.

When looking for a place to live, it is important to keep local sources in mind.  For instance, it is best to stay away from areas with a lot of industry and major roadways.  The impacts of emissions from vehicles on a highway or any roadway depend on a number of factors, including:  the distance from the highway; traffic volume; traffic congestion (i.e. free flowing or congested); and predominant wind directions. 

Generally speaking, air concentration impacts from a highway decrease significantly with distance from the roadway.  Typically, moving 100 metres from the edge of the road can result in a decrease in pollutant concentrations of 60-80 per cent.  In addition, trees can filter the air, so a well-treed area can have better air quality than one without trees.


What is air pollution?

There are many different types of air pollutants from a wide range of sources. The pollutants that most affect health are the gases and particles that contribute to cardiovascular and respiratory disease. These pollutants are often lumped together under the term “smog”.


Where does smog come from?

The contaminants that create smog are released during the combustion of fossil fuels in our vehicles, power plants, factory boilers and homes. They are also released by industrial processes, the evaporation of liquid fuels and the use of solvents and other volatile products such as oil-based paints. Smog-causing contaminants are released during forest fires, and emitted by natural sources such as: trees, bogs, and volcanic activity. Most of Ontario's smog problems are caused by a combination of local emissions and pollutants carried by the wind from pollution sources in the United States. More than half of our smog problem comes from south of the border.


How is smog forecast?

The Ontario Ministry of the Environment and Climate Change and Environment Canada want to give Ontario residents the best tools to make decisions to protect their health by limiting short-term exposure to air pollution and adjusting their activity levels during increased levels of air pollution. To help plan your day, the ministry, in partnership with Environment Canada, issues a prediction of the Air Quality Health Index (AQHI) value for today, tonight and tomorrow. Since smog is tied to weather, meteorologists keep a close watch on short and long-range weather forecasts, and continually study air quality information concerning Ontario and neighbouring U.S. states. Pollution levels like weather, are very dynamic and can change at any time. To protect your health, it is important to regularly monitor both forecasts and reported Air Quality Health Index values.


Why does the Air Quality Health Index forecast look different in some locations?

Beginning June, 2015, the Ontario Ministry of the Environment and Climate Change and Environment Canada entered into a partnership to provide the Air Quality Health Index forecasts for the province of Ontario. As part of the agreement, Environment Canada meteorologists will be preparing the Air Quality Health Index forecasts for 17 locations across Ontario, including Windsor, London, Hamilton, St. Catharines, Burlington, Oakville, Mississauga, Brampton, Newmarket, Toronto, Oshawa, Peterborough, Kingston, Ottawa, Barrie, Dorset and Sault Ste. Marie. The remaining 16 locations across Ontario will be forecasted by the Ontario Ministry of the Environment and Climate Change. In January, 2016, Environment Canada will assume forecasting duties for all Air Quality Health Index locations across Ontario. During this transition, there will be differences between the forecasts from Environment Canada and those from the Ontario Ministry of the Environment and Climate Change. Environment Canada will be forecasting an Air Quality Health Index value for today, tonight, and tomorrow with their morning forecast, and for tonight and tomorrow with their afternoon forecast. The Ontario Ministry of the Environment and Climate Change will be issuing a forecast of the Air Quality Health Index for only today and tomorrow.


How does air pollution affect my health and the health of my family?

Depending on the length of time you are exposed, your health status, your genetic background and the concentration of pollutants, air pollution can have a negative effect on your heart and lungs. It 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 adverse health effects of air pollution.

Negative health effects increase as air pollution worsens. Small increases in air pollution over a short period of time can increase symptoms for those at risk.


How do I know if I am at risk?

People with diabetes, lung disease (such as chronic bronchitis, asthma, emphysema, lung cancer) or heart disease (such as angina, a history of heart attacks, congestive heart failure, arrhythmia or irregular heartbeat) are more sensitive to air pollution.

Seniors are at higher risk because of weakening of the heart, lungs and immune system and increased likelihood of health problems such as heart and lung disease.

Children are also more vulnerable to air pollution; they have less-developed respiratory and defense systems. Children also spend more time outdoors being physically active, which can increase their exposure to air pollution.

People participating in sports or strenuous work outdoors breathe more deeply and rapidly, allowing more air pollution to enter their lungs. They may experience symptoms like eye, nose or throat irritation, cough or difficulty breathing when air pollution levels are high.


What can I do to protect my health and the health of my family? How can I find out about the health risks posed by air pollution in my community?

You can better protect yourself and those in your care by understanding how air pollution affects your health, and by checking the Air Quality Health Index on a regular basis to find out what the health risks from air pollution are in your community.

To check the Air Quality Health Index reading for your community and to learn more about how air pollution can affect your health, visit the Ministry of Environment and Climate Changes web site.

We can protect our health by appropriately changing our behaviour to reduce our exposure to air pollutants when air quality worsens.

Ontarians can assess whether they are at greater risk based on their age, health status and level of outdoor physical activity, and if they are experiencing symptoms.

When the Air Quality Health Index reading rises, you can decide whether you or someone in your family needs to:

  • Reduce or reschedule outdoor physical activities
  • Monitor possible symptoms, such as difficulty breathing, coughing or irritated eyes
  • Follow a doctor’s advice to manage existing conditions such as heart or lung disease

You can also use the index as a reminder of the need to take action to reduce air pollution.


What is the Air Quality Health Index?

The Air Quality Health Index is a scale designed to help you understand what the quality of the air around you means to your health. It is a tool developed by health and environmental professionals to communicate the health risk posed by air pollution.

It is designed to help you make decisions to protect your health and the environment by:

  • Limiting short-term exposure to air pollution
  • Adjusting your activity during episodes of increased air pollution and encouraging physical activity on days when the index is lower
  • Reducing your personal contribution to air pollution

The Index provides specific advice for people who are especially vulnerable to the effects of air pollution as well as the general public.


What is the difference between the Air Quality Index I am used to and the Air Quality Health Index?

The Air Quality Health Index is a new approach to communicating about air quality that offers more protective health information. The Air Quality Health Index presents the immediate health risk of the combined effects of the air pollution (smog) mixture.

The Air Quality Health Index is a personal health protection tool for individual Ontarians, especially those most at risk: children, seniors, and people with diabetes, heart and lung disease. The old Air Quality Index had a scale of 0-100+, with values usually in the range of 10-60, and poor air quality designated as values above 50. The Air Quality Health Index is a simplified scale from 1-10+ with three categories “low, moderate and high risk” within this range.


When did Ontario stop reporting the Air Quality Index?

In June 2015, in partnership with Environment Canada, the Ontario Ministry of the Environment and Climate Change adopted the national Air Quality Health Index to report air quality in Ontario.


Where can I find historical Air Quality Index data?

Data from the old Air Quality Index (AQI) is available for 2007-2014 in our Historical AQI Data Set.


What can the Air Quality Health Index tell me about the health risks I may experience due to the current local air quality?

The Air Quality Health Index provides a number from 1 to 10+ to indicate the level of health risk associated with local air quality. Occasionally, when the amount of air pollution is abnormally-high, the number may exceed 10.

The higher the number, the greater the health risk and our need to take precautions.

The index describes the level of health risk associated with this number as ‘low’, ‘moderate’, ‘high’ or ‘very high’, and suggests steps we can take to reduce our exposure.

It also forecasts local air quality and provides associated health advice.

The index does not measure the effects of odour, pollen, dust, heat or humidity on your health.

You can refer to the Air Quality Health Index to check the quality of outdoor air in your community before heading off to work or play. And you can use the forecasts to plan your activities, whether over the next hour or the next day.

Seniors, children and people suffering from diabetes, heart or lung disease, can use the index to assess the immediate risk air pollution poses to your health and take steps to lessen that risk.

Even if you’re relatively healthy, fit and active, you can consult the index to decide when and how much to exercise or work outdoors.


How should I respond to Air Quality Health Index information about health risks?

The table below provides the health messages for each category of the Air Quality Health Index for the "at risk" population and the general population.
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 10 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.

* People with heart or breathing problems are at greater risk. Follow your doctor's usual advice about exercising and managing your condition.


How is the Air Quality Health Index presented?

The Air Quality Health Index is a scale that lists a number from 1 to 10+ to indicate the level of health risk associated with air quality.

Air Quality Health Index Categories, Values and Associated Colours
1
2
3
4
5
6
7
8
9
10
+
Low Risk
(1 - 3)
Moderate Risk
(4 - 6)
High Risk
(7 - 10)
Very High Risk
 

Scientists created the index by estimating the daily change in mortality risk for ten cities from 1998-2000 and plotting it on a 10 point scale.

The higher the number, the greater the risk and the need to take precautions.


What is the scale for the Air Quality Health Index?

The Air Quality Health Index is measured on a scale ranging from 1 to 10+:

  • 1-3 = ‘Low’ health risk
  • 4-6 = ‘Moderate’ health risk
  • 7-10 = ‘High’ health risk
  • Above 10 = ‘Very high’ health risk

Why does Environment Canada show only one number for Toronto, Windsor, Hamilton and Ottawa, but there is one for each individual station on this website?

In areas of Ontario where there are more than one Air Quality Health Index monitoring station, Environment Canada reports and forecasts a community value. This value is produced by averaging information from the air monitoring stations in the local area. For example, Environment Canada’s Toronto community value is based on the measurements from the Toronto Downtown, Toronto East, Toronto North and Toronto West air monitoring stations. Ontario reports the AQHI values for each station and adopts the community forecast provided by Environment Canada.


How is Ontario's Air Quality Health Index calculated?

The formula developed to calculate the Air Quality Health Index is based on research conducted by Health Canada using health and air quality data collected in major cities across Canada.

The Air Quality Health Index represents the relative risk of a mixture of common air pollutants which are known to harm human health. Three pollutants were chosen as indicators of the overall outdoor air mixture:

  • Ground-level ozone (O3)
  • Fine particulate matter (PM2.5)
  • Nitrogen dioxide (NO2)

In Ontario, the AQHI number also considers hourly comparisons of individual pollutant concentrations to Ontario’s Ambient Air Quality Criteria (AAQC).

If hourly air pollutant concentrations are higher than Ontario’s AAQC, and the AQHI value is in the low or moderate risk categories, then the Air Quality Health Index value is replaced with the appropriate High or Very High risk value. This adjustment is relevant for:

  • Ozone
  • Nitrogen dioxide (NO2)
  • Sulphur dioxide (SO2)
  • Carbon monoxide (CO)
  • Total reduced sulphur (TRS) compounds

If the following pollutant thresholds are exceeded when the Air Quality Health Index is Low or Moderate risk (6 or less), then the AQHI is replaced with the appropriate High or Very High risk value (7 or greater):

  • 80 parts per billion for ozone
  • 200 parts per billion for nitrogen dioxide
  • 250 parts per billion for sulphur dioxide
  • 30 parts per million for carbon monoxide
  • 27 parts per billion for and total reduced sulphur compounds

Is it possible to have high risk Air Quality Health Index even if a Special Air Quality Statement or Smog and Air Health Advisory has not been issued?

Yes. Since smog is closely tied to the weather, it is impossible to be 100 per cent accurate 100 per cent of the time. For example, a weather system could arrive in Ontario before the predicted time, or could change direction.

High risk Air Quality Health Index values could occur without a Special Air Quality Statement (SAQS) or Smog and Air Health Advisory (SAHA) being issued. It is also possible that high risk Air Quality Health Index will not materialize even though a Smog and Air Health Advisory or Special Air Quality Statement has been issued.


How can I get air quality information?

  1. On this website: http://www.airqualityontario.com. This site provides Air Quality Health Index (AQHI) readings and forecasts, ambient air pollution data, as well as information on actions that can be taken when a Special Air Quality Statement (SAQS) or Smog and Air Health Advisory (SAHA) is issued.
  2. The Environment Canada website www.ec.gc.ca/cas-aqhi/, where AQHI readings and forecasts are posted, as well as information regarding any current SAQS and/or SAHA that have been issued.
  3. You can sign up to Environment Canada’s Alert Me service at https://ecalertme.weather.gc.ca to receive an automatic email when any SAQS or SAHA is issued in your selected region(s). This service also allows you to receive additional notification of many other types of watches, warnings or statements issued by Environment Canada if you are interested.
  4. By telephone: You can get AQHI readings from recorded telephone messages by dialing 1-800-387-7768 (toll-free) or 416-246-0411 in Toronto. To obtain AQHI readings in French, dial 1-800-221-8852.
  5. Via radio and television: The MOECC has worked for many years with news media across Ontario to inform the public about smog conditions. This will continue to be a crucial method for communicating information about smog and actions that can be taken to reduce smog-causing emissions

Where can I obtain hourly pollutant concentration data?

The Ontario Ministry of the Environment and Climate Change’s Air Quality Index web site provides users with access to hourly pollutant concentration data from the ministry's ambient sites. The data output, which includes station and pollutant information, is available in both .HTML and/or .CSV format(s) which may be imported directly into Excel or any other spreadsheet application. The tool may be accessed at: http://www.airqualityontario.com/history/


How is PM2.5 monitored in Ontario?

In 2002, Ontario was the first province in Canada to introduce monitoring of PM2.5 to the Air Quality Index. The ministry reported real-time PM2.5 with the Thermo Scientific TEOM 1400AB/SES until December 31, 2012. Continuous PM2.5 monitoring technologies have evolved dramatically over the last decade. The network is now reporting real-time PM2.5 concentrations using Thermo Scientific SHARP 5030, an approved Class III Federal Equivalent Method designated by the United States Environmental Protection Agency in 2009. Ontario evaluated the SHARP monitor starting in 2009, and adopted this method in 2012 in concurrence with Environment Canada. In 2013, the SHARP monitors were deployed across Ontario's air quality monitoring network.


What is the effect of the SHARP PM2.5 monitor on reported PM2.5 concentrations?

The new SHARP monitor is able to detect additional components of PM2.5, especially during cold weather. As a result of this improvement in monitoring technology, there is potential to report higher PM2.5 concentrations during the winter months. This is a reflection of more accurate measurements and does not necessarily mean that Ontario's air quality is changing. The air is the same; only the monitoring method has changed.


Why did Ontario upgrade the PM2.5 monitoring network?

Ontario strives to be a leader in air quality reporting and continues to benefit from one of the most comprehensive air monitoring systems in North America. The network upgrade was funded by Environment Canada under a national initiative to standardize PM2.5 monitoring methods across Canada and ensure data comparability. The objective is to have all jurisdictions operating federally approved PM2.5 monitors by 2013.


What is the purpose of Special Air Quality Statements and Smog and Air Health Advisories?

The purpose of these alerts is to advice people with breathing difficulties to avoid unnecessary exposure to smog. They also inform industries that are major sources of pollution that they should consider, if possible, reducing their emissions. Additionally, they solicit everyone's help in lessening the problem by curtailing activities that produce smog.


What should I do if a Special Air Quality Statement or Smog and Air Health Advisory is issued?

Here are some actions you can take to help protect the environment and your own health:

At home:

  • Conserve electricity year-round by adjusting the heat or air conditioner and turning off lights you are not using.
  • Avoid letting your car, or any other engine, idle for long periods.
  • Reduce your use of gasoline-powered equipment.
  • Avoid mowing the lawn when air quality is poor.
  • Don't use oil-based products such as paints, solvents or cleaners if you can avoid them. They contain volatile organic compounds (VOCs), which contribute to smog.
  • Avoid or reduce strenuous physical outdoor activities when smog levels are high, especially during the late afternoon. Do not exert yourself outdoors.
  • If possible, stay indoors in a cool, air-conditioned environment.
  • Get engine tune-ups and car maintenance checks as advised by the car manufacturer's maintenance schedule.
  • Limit the amount of wood you burn in your fireplace or woodstove. When burning wood, use only the dry, seasoned variety.

At work:

  • If possible, take public transit, or walk to work.
  • If you use a car, don't travel alone; encourage and facilitate car pooling.
  • Avoid traffic congestion.
  • Consider teleconferencing, instead of traveling to meetings.

As always, consult your doctor for specific medical advice on how to cope with poor air quality.


What is the difference between a Special Air Quality Statement (SAQS) and a Smog and Air Health Advisory (SAHA)?

If a high risk Air Quality Health Index value is forecast to last for 1 to 2 hours, then a Special Air Quality Statement (SAQS) will be issued. The purpose of a Special Air Quality Statement is to be precautionary and to be vigilant of your health as it relates to the Air Quality Health Index.

If the high risk Air Quality Health Index is forecast to be persistent, a duration of at least 3 hours, then a Smog and Air Health Advisory (SAHA) will be issued.

Both Special Air Quality Statements and Smog and Air Health Advisories are issued jointly by Environment Canada and the Ontario Ministry of the Environment and Climate Change.


How many Special Air Quality Statement (SAQS) and Smog and Air Health Advisory (SAHA) were issued in previous years?

Special Air Quality Statements and Smog and Air Health Advisories issued for Ontario since 2015.
Year SAQS SAHA
201560

* as of July 29, 2015.


Can I compare Special Air Quality Statements or Smog Air Health Advisory statistics to historical smog advisory statistics?

Special Air Quality Statements (SAQS) and Smog and Air Health Advisories (SAHA) are very different than the smog advisories that were issued in the past. Special Air Quality Statements and Smog and Air Health Advisories are issued based on the Air Quality Health Index, which presents the immediate health risk of the combined effects of the air pollution (smog) mixture and has a simplified 1-10+ scale. Smog advisories were issued based on the old Air Quality Index which had a 0-100+ scale and reflected Ontario’s Ambient Air Quality Criteria (AAQC). Because of these differences, the Special Air Quality Statements and Smog and Air Health Advisories should not be compared with the smog advisories that were issued in the past.

If you would like to look at historical smog advisory statistics, please visit Historical Smog Advisory Statistics.


What is Ontario doing to improve and protect air quality?

Ontario is committed to doing its part to reduce emissions and improve air quality and is doing so through several programs and initiatives including:

  • Drive Clean – a program that reduces nitrogen oxides (NOX) and volatile organic compounds (VOCs) through emissions testing of motor vehicles and enforcement through the Smog Patrol;
  • Phasing out Coal – Ontario’s coal phase-out is yielding the most significant results of any climate change initiative in North America to date. In 2014, Ontario was the first jurisdiction In North America to eliminate coal as a source of electricity production.
  • Greener Fuel Requirements – On March 31, 2014, Ontario filed a greener diesel regulation, O. Reg. 97/14, “Greener Diesel – Renewable Fuel Content Requirements for Petroleum Diesel Fuel”. Expanding the use of greener diesel fuels will help improve air quality and reduce greenhouse gas emissions in the transportation sector, the largest and fastest growing contributor of greenhouse gas emissions in Ontario.
  • Implementing a Climate Change Action Plan – which includes targets of:
    • 6 per cent below 1990 emission levels by 2014;
    • 15 per cent below 1990 levels by 2020; and
    • 80 per cent below 1990 levels by 2050.
  • Strict air standards – establishing and enforcing air quality standards for pollutants to protect local communities;
  • Green Energy – Developing cleaner sources of energy like wind and solar to replace coal-fired generation

Why is the Air Quality Health Index not available in my region?

Ontario’s air monitoring network is comprised of stations representing urban, rural, road-side and transboundary air quality, so it is able to provide a complete picture of the air quality across the province.