A Health-based National Air Quality Index

Air pollution is associated with thousands of premature deaths per year in Canada. It has been clearly linked to respiratory diseases such as asthma and bronchitis, and can negatively impact pre-existing health conditions such as diabetes and heart problems. Pregnant women, children and the elderly are especially at risk of experiencing the adverse effects of exposure to air pollution.

The health effects of air pollution lead to increased hospitalizations and visits to the emergency room or the doctor's office, all of which strain the Canadian health care system. They also cause Canadians to miss more days at school or work, which in turn impacts the country's economy.

Canadian Air Quality Indices

Canadians rely on the Air Quality Index (AQI) to stay informed, on a daily basis, about air pollution conditions in their communities.

The AQI is a communications tool. It is used to report upon current and near term air quality conditions. It provides a general idea of the level of air pollution at a particular place and time. A numerical value on a scale and a rating such as "good" "fair" or "poor" is used to inform the public of air quality conditions without reporting concentrations of individual pollutants. Some of the pollutants captured in currently reported Canadian AQIs are: sulphur dioxide, ozone, nitrogen dioxide, total reduced sulphur compounds, carbon monoxide and fine and coarse particulate matter.

AQIs are issued by provinces, territories and some regional districts or municipalities. The federal government provides scientific, technical and monitoring support in support of their mandates. Of particular importance are air quality forecasts, as issued by Environment Canada which assist those responsible jurisdictions with predicting air quality conditions.

AQI readings are based on whichever pollutant is highest at the time of measurement or predicted to be within a forecast period. The higher the number, the poorer the air quality. Sub-indices are calculated for each of the available pollutants which equate to AQI values. The highest AQI value and the pollutant are reported as the AQI.

Although they differ slightly, the presentation of AQI generally reflects a scale from 0-100 and a range of categories between very good to very poor. In Ontario, for example, "good" means there is relatively low levels of air pollution, a "moderate" reading means the levels of air pollutants may cause possible adverse effects on very sensitive people, a "poor" reading can cause possible short-term adverse effects on the human or animal populations, or significant damage to vegetation and property, and a "very poor" reading means that the pollution levels can cause possible adverse effects on a large proportion of those exposed.

An air quality advisory is called when the calculated sub-indices of the pollutant concentration exceed an AQI value of 50 for a fixed period of time which is the point where it is determined that air quality goes from moderate to poor.

AQI advisories, and the health messages associated with the advisories, are reported to the public and the media at set intervals each day. With this information, individuals can then decide how to reduce the risk to their health, as well as reduce their own personal contribution to air pollution.

Advisories warning of extreme conditions, particularly during the summer months, are more commonly known as "smog alerts". Some of the advice you are likely to hear during smog alerts include:

• Listen to the radio or watch television reports for information about air quality and smog advisories. Plan your day based on this information.
• Consider limiting or rescheduling physical outdoor activities on smog advisory days when air pollution is more harmful than usual.
• Reduce exposure to motor vehicle exhaust by limiting physical activity near heavy traffic areas, particularly at rush hour.
• Stop unnecessary vehicle idling. This is an easy way to help improve the air quality in your community.

There is currently little national consistency in how AQIs are reported. An AQI of 50 does not mean the same in Vancouver and Montreal for example. The pollution thresholds, the pollutants included in the AQI formulation and the choices surrounding calling the advisory vary depending on jurisdiction.

In addition, the thresholds used in determining AQI levels and categories are based on outdated health science and tend to reflect environmental regulatory imperatives rather than implications for human health. These and other concerns form the basis for the current exercise to improve the state of Canadian AQIs.

Development of a new Canadian AQI

In June 2001, the Government of Canada began working with variety of stakeholders including provincial and municipal governments, health and environmental stakeholders and the media to address the short-comings of the current AQI with a specific focus on making it more health-based. In the spring of 2002, a decision was taken by the stakeholders to proceed with the development of a health-risk based AQI. The scientific foundation for the new health risk based index is based on the cutting-edge epidemiological research undertaken by Drs. Burnett, Stieb and others at Health Canada.

This will be the first air quality index of its kind in the world. The challenges of the undertaking are as significant as are the benefits.

A cornerstone of this process is the development of relevant and timely health messages to empower Canadians to safeguard their own health and those in their care and to motivate change in improving air quality in their communities.

Health Canada is undertaking research and stakeholder consultations to determine:

• how familiar Canadians are today with Air Quality Index advisories in their provinces and municipalities;
• public attitudes, beliefs and behaviours related to the Air Quality Index;
• what air quality messages Canadians currently receive; and
• Canadian attitudes and expectations, input and recommendations related to air quality health messaging in order to develop more effective and informative messages in the future.

Development of a Health-based Air Quality Index For Canada - Public Opinion Research 2004-05 (Executive Summary)

For more information, read Environment Canada's backgrounders on the
Air Quality Index and Air Quality Forecasting

For information on the AQI process
http://www.msc-smc.ec.gc.ca/caqi/index_e.cfm
http://www.ec.gc.ca/press/2003/030623-3_b_e.htm

To find out more about what to do on smog alert days to help improve air quality, visit
Environment Canada's Clean Air Web site

For links to Canadian air quality information and issued AQIs and those of other countries
http://www.msc-smc.ec.gc.ca/CAQI/links-liens_e.cfm
http://www.msc-smc.ec.gc.ca/CAQI/links-liens_f.cfm?