The air monitoring stations measure up to 6 common pollutants like: * ground-level ozone * fine particulate matter * nitrogen dioxide * carbon monoxide * sulphur dioxide * total reduced sulphur compounds The Ministry of the Environment, Conservation and Parks continually monitors air quality across Ontario. We use this information to: * inform the public about outdoor ambient air quality through the Air Quality Index (AQI) and Smog Advisory program * assess Ontario's air quality and evaluate long-term trends * identify areas where pollutant levels are exceeded * identify the origins of pollutants * develop air policy * provide quantitative measurements to reduce specific pollution sources * determine the significance of pollutants from long-range transports and their effects * provide air quality researchers with data to link environmental and human health effects to air quality