WINNIPEG AIR QUALITY INDEX
Information Brochures and Reports

An Air Quality Index (AQI) is a system for rating air quality in urban areas. It provides the public with a general idea of air quality in their community.

The Index scale provides a number and a description:

Good 0 - 25,
Fair 26 - 50,
Poor 51 - 100, or
Very Poor over 100.

The lower the number, the better the air quality.

Manitoba's air quality objectives (standards) are based on the federal government's air quality objectives (standards). They are designed to protect public health and the environment. The AQI categories generally correspond to air pollution levels described in the objectives.

The AQI considers 5 common pollutants (see section on Index Pollutants) which effects human health or the environment at specific air concentration levels.

The Index was developed as a cooperative project of Manitoba Conservation, Environment Canada, and the Manitoba Lung Association, with the assistance of Manitoba Health and Health Canada.

Why do we need an AQI in Winnipeg?

Air quality in Winnipeg is good nine days out of every ten. However, there are times when the air quality deteriorates and may cause health problems for people with respiratory problems and the public at large. The AQI serves the following purposes:

• to promote awareness of air quality in Winnipeg
• to preserve good air quality (as a preventive measure), and
• to tell Winnipeg residents when air quality has deteriorated (as a precautionary advisory.)

Similar AQI systems operate in Calgary, Edmonton, Montreal and many other Canadian cities

Determination of the AQI

Manitoba Conservation, as part of the National Air Pollution Surveillance (NAPS) Program, monitors the air in Winnipeg around the clock for the following pollutants:

• Carbon Monoxide (CO)
• Fine Particulates (COH and PM10)
• Ground-Level Ozone(O3), and
• Nitrogen Dioxide (NO2).

Each hour, the level of each pollutant is converted to the index scale, yielding a sub-index for each one. The highest sub-index value (for the pollutant posing the most risk) becomes the value for the overall Index.

For example, if the pollutant with the highest sub-index was ground-level ozone at a value of 38 (Fair), the AQI would appear on Cable TV as follows:

Winnipeg Air Quality Index at (time of day) is Fair at 38 due to Ozone (smog). Noticeable health effects are unlikely. Info: 945-7044

How do I interpret the AQI?

The objective of the AQI is to describe the current quality of the air and its potential impact on the environment. Air Quality Index values are divided into four ranges. General impacts associated with each range are as follows:

• "Good" : no effects.
• "Fair" : noticeable health effect unlikely, some environmental effects may be observed.
• "Poor" : some people, especially those with pre-existing health problems may notice health effects, some environmental effects may be observed.
• "Very Poor" : health effects may be experienced by all and especially those with existing respiratory conditions, some environmental effects may be observed.

Each range is further described with a message about possible health and environmental risks. For the complete text of the messages call Manitoba Conservation at 945-7044.

Where are AQI reports available?

Environment Canada reports the AQI through the weather information channel on Cable TV (Videon - channel 9, Shaw - channel 35) and on its weather information telephone line at 983-2050. Each is updated hourly.

Manitoba Conservation publishes annual ambient air quality monitoring reports. These reports describe the monitoring programs and present a summary and evaluation of the air quality, and can be obtained from:

Manitoba Conservation, Air Quality Management
123 Main Street, Winnipeg, MB R3C 1A5

What can I do?

Winnipeg residents are fortunate to enjoy good air quality most of the time. All residents are encouraged to help maintain our good air quality through increased awareness of the Air Quality Index and by making environmentally friendly choices. Vehicle emissions, for example, are a major cause of air pollution in most cities, including Winnipeg. By using cleaner fuels, properly maintaining our vehicles and choosing to drive our vehicles less often, we will reduce air pollution and help preserve one of Winnipeg's most valuable assets - our fresh, clean air.

For further information about air quality and the Air Quality Index system in Winnipeg, please contact Manitoba Conservation at 945-7044.

Index Pollutants and Measurement periods

Carbon Monoxide (CO) 1 hour and 8-hour running average

Carbon monoxide is a colourless, odourless, tasteless gas slightly heavier than air. CO replaces oxygen in the red blood cells and this lack of oxygen reduces the ability of the body to function. First symptoms are impaired perception and reflexes and a reduced tolerance for physical activity. Motor-vehicle exhaust accounts for 80% of the emitted CO. Other sources include fossil fuel combustion for building, heating and commercial and industrial operation.

Inhalable Particulates (PM10) 24-hour running average

Inhalable particulates are suspended fine particles with diameters between 0.1 and 10 microns, in solid or liquid form, that can reach the lungs. The particles may remain suspended in the air in the form of dust, smoke, fumes, aerosols, soot, mist, etc. Many common industrial processes including combustion, incineration, and metal smelting are sources of these fine particles. Another source is motor vehicle exhaust. Natural sources include windblown dust, forest fires, ocean spray, and volcanic activity. Elevated levels of PM10 can aggravate existing respiratory problems and may result in long term effects on the lungs.

Soiling Index (COH) 1 hour and 24-hour running average

The soiling index or coefficient of haze (COH) is an indication of the soiling or darkening potential of fine particulates in the atmosphere, usually resulting from combustion. The particles may remain suspended in the air as dust, smoke, fumes, aerosols, soot, or mist. These particulates, usually in the size range from 0.1 to 1 micron (fine particles) in solid or liquid form, can become trapped in the lungs during breathing. They can cause soiling, decrease visibility, aggravate respiratory problems, and may cause long term effects on the lungs.

Nitrogen Dioxide (NO2) 1 hour

Nitrogen dioxide is a reddish-brown gas with a pungent, irritating odour when it's concentration in air exceeds over 0.10 parts per million (ppm). NO2 exerts its primary adverse effect on the lungs and can contribute to a worsening of existing respiratory conditions and loss of elasticity in the lungs. NO2 also suppresses vegetation growth, causes corrosion of metals, reduces visibility, and helps form harmful ground level ozone. All combustion processes are sources for NO2 including vehicles, power plants, heating systems, and incinerators.

Ozone (O3) 1 hour

Ozone is a pungent, colourless gas and a major component of smog. Ozone is not directly emitted to the atmosphere; instead, at ground level, it is produced in the air when nitrogen oxides and volatile organic compounds emitted by cars and industrial processes react with sunlight. Because ozone production requires warm temperatures and sunny conditions, high ozone levels in Manitoba usually occur between the months of May and September. It does not breakdown easily and can sometimes be carried far way from where it is created. Ozone can irritate the eyes and the nasal passages and worsen existing respiratory problems. In addition there is evidence that exposure to elevated ozone levels results in long term effects on the lungs. Ozone reduces crop yields, injures vegetation and weakens materials such as rubber and certain fabrics.

Ground-level ozone is not the same as the naturally occurring "ozone layer" high in the atmosphere. The ozone layer is found in the stratosphere 25 km above the surface of the earth, and protects the earth from ultraviolet radiation.

Manitoba Conservation gratefully acknowledges the cooperation and support of Environment Canada and the Manitoba Lung Association in the production of this fact sheet.

 

June, 1995