Modelling refers to a set of scientific methods that are used to represent the complicated processes that govern meteorology and the behaviour of pollutants in the atmosphere. Modelling is used to
identify the sources that contribute to poor air quality and to project air quality changes for different "what if" scenarios: e.g., what would happen to the air quality if a new highway, industrial
or housing development were built? In this way, modelling helps to inform decisions on how to maintain and improve air quality.
There are hundreds of different kinds of models used for air quality management. Some are very simple, others are very complex. Some common types of models include:
- Dispersion models — which use equations to represent the way that pollutants travel in the air in order to calculate the downwind air concentrations that result from emitting something into the air;
- Receptor models — where the properties of the air pollutants are able to identify and quantify the sources of air pollutants;
- Meteorological models — which use equations that represent the behaviour of the atmosphere, in order to predict the meteorological conditions at specific locations and forecast what these conditions will be in the future;
- Physical models — small scale reproductions used in wind tunnels to simulate actual conditions; and
- Statistical models — where statistics are used to provide a link between emissions and the resulting concentrations.
The provincial government's involvement in air quality modelling includes:
- conducting modelling to support air quality management decisions;
- providing modelling guidance;
- conducting reviews and making decisions on the acceptability of dispersion modelling submitted by consultants to the Ministry of Environment in support of permit applications and environmental assessment;
- collecting meteorological and air quality data in support of air quality modelling.
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