For the 2008 reporting year, over 8700 facilities reported to the NPRI on more than 3000 listed substances. Comprehensive air pollutant emission summaries and trends were compiled by Environment Canada for criteria air contaminants (the main pollutants contributing to smog, acid rain, and/or poor air quality), selected heavy metals, and persistent organic pollutants.
The NPRI is Canada's legislated, publicly-accessible inventory of pollutant releases (to air, water and land), disposals, and transfers for recycling. The NPRI comprises: