B.C. Air Quality

Receptor Modelling

Monitoring air quality can tell us a lot about the risk to local human health and it can tell us about seasonal, daily or even hourly conditions. However, by itself, monitoring can not tell us where the pollution is coming from or what the relative contribution from different emission sources is. Common emissions sources include wood stoves, forest fires, vehicles, industrial stacks and road dust.

To help air quality planners and decision-makers determine the sources behind bad air quality, and develop plans to reduce air pollution, scientists use a variety of source apportionment tools. In air pollution research, source apportionment is the task of determining sources of air pollutants and assigning or "apportioning" the relative contribution of each unique source to overall air quality.

Speciation Monitor

A speciation monitor collecting
air quality samples

A traditional approach is to use dispersion modelling where a pollutant emission rate and meteorological information are input to a mathematical model that "disperses" (and sometimes, chemically transforms) the pollutant, and predicts into the future what the air quality will be like at a certain place and a certain time.

Receptor modelling is a newer approach to source apportionment and has been developed using more and more complex models over the last 30 years. Unlike dispersion modelling, receptor modelling cannot predict future air quality but, instead, looks at past data collected at one site over a specific time period to determine the sources to that site.

Data for the model is collected using a speciation sampler (pictured above), which takes integrated samples over a 24-hour period from ambient air. These samples are analysed by a lab for a suite of chemical components.

The speciated data is then plugged into a computer model. The output of the model provides groupings of chemical species which are then interpolated as emission sources. The end result of the models resembles a "recipe" of air pollutant sources, and their respective contribution to the overall air quality at the site.

Current Receptor Modelling in British Columbia

There are three active speciation monitors running in British Columbia: Quesnel, Abbotsford and Burnaby. Receptor modelling has been performed in several B.C. communities — including Golden, Prince George, Kelowna and Burnaby. Reports on the Golden and Prince George studies are available in the Reports and Publications section.

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