Collecting the data

How we collect data for the Pollution Inventory

The Pollution Inventory (PI) provides information on emissions of chemical pollutants from industrial sites in England and Wales regulated by us.

Since 1998, the data has been collected systematically on an annual basis to include all emissions of a specified list of pollutants. Emissions to air, water and sewers are reported. Data is also collected on wastes that are transferred off-site to a disposal or recycling facility.

Data from major industry such as power stations, chemical works and the metal and mineral industries has been collected since 1998. Data from landfill sites and waste transfer stations started being reported in 2002. Data from sewage treatment works was first collected in 2000, but only from the largest works for a limited number of substances. In subsequent years, data for smaller sewage treatment works has been collected for the full list of Pollution Inventory substances.

Sites that dispose of radioactive substances began reporting their radioactive emissions in 2000, but reporting only became compulsory in 2004. These organisations include nuclear power stations, universities and hospitals.

The data is supplied each year by the industrial operator as a legal requirement. We then verify and audit it to confirm that it is correct, prior to publication on this website.