Industrial sites release millions of tonnes of chemicals each year into the environment. Major industries have to report how much of certain chemicals have been released into the environment - through chimneys, outfall pipes, sewers, leaked accidentally or produced as solid waste.
The data forms the "Chemical Release Inventory", CRI. It is public information and allows you to find out about releases of chemicals reported from sites near you.
The data reports are collected together by HMIP (Her Majesty's Inspectorate of Pollution) - who are responsible for issuing permits (called authorisations) to industrial sites for major processes. A site may be operating many different processes, each with a separate authorisation. The authorisation numbers are always 2 letters followed by 4 numbers (eg AB1234).
Other sources for this informtion:
The files at HMIP regional and Local Authority offices are public and must be available for inspection.