Additionally, TRI chemical releases at a given facility are not indicators of whether a facility is violating environmental laws. Most of the chemicals reported under the EPA's TRI are allowable under existing permits. Mining companies anticipate they have reported greater volumes under TRI than other industry categories because mining operations must move and process large quantities of rock to remove the needed metals. Electric utilities that combust coal or oil are also reporting for the first time, additionally increasing TRI numbers for Arizona. Electric utility releases typically result from low concentrations of chemicals released in large volumes of air from stacks.
Releases also result from bottom and fly ash, slag, and control wastes.
The releases may include hydrochloric, hydrofluoric and sulfuric acids from chemical reactions from burning coal. It was designed to provide the public with information about chemicals and other substances used in manufacturing. In 1998, the list of substances was expanded, bringing the total number of reportable substances was expanded to 644. Since the TRI is an EPA program, ADEQ's role has been limited to receipt of the EPA mandated reports and answering facilities' questions on TRI reporting requirements. ADEQ has not performed an analysis of the TRI data.