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Monitoring Air Quality

On May 1, 2000, six new rural and three urban air quality monitoring stations were added to Ontario's Air Quality Index (AQI) network, making a total of 33 state-of-the-art air quality monitoring stations across the province. Each AQI site is equipped with air monitoring equipment that measures some or all of the six most common air pollutants (sulphur dioxide, ozone, nitrogen dioxide, total reduced sulphur compounds, carbon monoxide and suspended particles)

The Air Quality Index (AQI) is a rating scale for outdoor air in Ontario. The lower the AQI, the better the air quality.

Based on data from its network of air monitoring stations, the Ministry of the Environment reports an AQI for many communities across Ontario to all major media outlets and the Ministry web site several times daily.

The air monitoring data are sent to a computer centre at the ministry. Data are compared to an ambient air quality criterion (AAQC) for each of the six air pollutants. These scientifically-based criteria, which are updated from time to time, indicate the maximum safe level for a pollutant. Above this level, the pollutant begins to have an undesirable impact on people and the environment.

Using the AAQC, the monitoring data are converted into the AQI scale. The scale ranges from 0-15 (good) to 100+ (very poor).

The misitry then conmes out with uits forecast. Since a forecast is a prediction for the future, the good, moderate or poor ratings are not based on actual, real time data.

    Good quality air means the air quality index (AQI) reading is expected to range from 0 to 31 (the air quality is good and there are no known health effects for the majority of the population..

    Moderate means the AQI reading may range from 32 to 49 (there may be some adverse health effects for very sensitive people).

    Poor means the AQI reading may be over 50. (there may be some adverse effects on the most sensitive people and animals, or there be damage to vegetation and property)

    Very poor — above 100: the health of a large number of people and animals as well as plant life and property may be affected..

A poor reading triggers a smog watch or smog advisory.

The ministry wants to give Ontario residents as much notice as possible if it looks as though a smog day is on the way. There are two kinds of smog alerts that could be called. When there is a 50 per cent chance that a smog day is coming within the next three days, the ministry issues a smog watch. When there is a strong likelihood that a smog day is coming within the next 24 hours, a smog advisory is called.

Source: www.airqualityontario.com/index.cfm