"The National Pollutant Inventory (NPI) is an internet database designed to provide the community, industry and government with information on the types and amounts of certain chemicals being emitted to the environment...
The US was one of the first nations to introduce legislation to mandate emissions reporting by industry. The US EPA explains why it was introduced:
In 1984 a deadly cloud of methyl isocyanate killed thousands of people in Bhopal, India. Shortly thereafter there was a serious chemical release at a sister plant in West Virginia. These incidents underscored demands by industrial workers and communities in several states for information on hazardous materials. Public interest and environmental organizations around the country accelerated demands for information on toxic chemicals being released "beyond the fence line" --outside of the facility. Against this background, the Emergency Planning and Community Right-to-Know Act (EPCRA) was enacted. Hailed as one of the most potent pieces of environmental legislation in 20 years, EPCRA's primary purpose is to inform communities and citizens of chemical hazards in their areas.
Source: Office of Pollution Prevention and Toxics, 'What is the Toxics Release Inventory?', US EPA, http://www.epa.gov/opptintr/tri/general.htm, 11 May 1999.