Air emissions reported to TRI continue to decline, serving as a primary driver of decreased total releases. Air releases include both fugitive air emissionsfugitive or non-point air emissionsAll releases of the EPCRA Section 313 chemical to the air that are not released through stacks, vents, ducts, pipes, or any other confined air stream. and point source air emissionsstack or point air emissionsAll releases of the EPCRA Section 313 chemical to the air that occur through stacks, confined vents, ducts, pipes, or other confined air stream..
This graph shows the trend in the pounds of chemicals released to air.
From 2007 to 2017:
- Air releases declined significantly, serving as a primary driver of decreases in total releases.
- Air releases decreased by 57% (757 million pounds).
- Hydrochloric acid, sulfuric acid, hydrogen fluoride, methanol, toluene and styrene were the chemicals with the greatest reductions in air releases since 2007.
- The decrease is driven by electric utilities due to: decreased emissions of Hazardous Air Pollutants (HAPsHAPsChemicals that cause serious health and environmental effects. Health effects include cancer, birth defects, nervous system problems and death due to massive accidental releases such as the one at the pesticide plant in Bhopal, India. Hazardous air pollutants are released by sources such as chemical plants, dry cleaners, printing plants, and motor vehicles (cars, trucks, buses etc.)),such as hydrochloric acid; a shift from coal to other fuel sources (e.g., natural gas); and the installation of control technologies at coal-fired power plants. Note that only those electric utilities that combust coal or oil to generate power for distribution into commerce are covered under TRI reporting requirements. Therefore, electric utilities that shift from combusting coal or oil to entirely using other fuel sources (such as natural gas) no longer report to TRI.
- Electric utilities accounted for 92% of nationwide reductions in air releases of hydrochloric acid and sulfuric acid from 2007 to 2017.
- Air releases of Occupational Safety and Health Administration (OSHA) carcinogens also decreased; see the Air Releases of OSHA Carcinogens figure.
- Air releases of other chemicals of special concern, including lead and mercury, also decreased; see the Chemicals of Special Concern section.
- Air releases are often regulated by other programs as well, such as under Title V of the Clean Air Act, which requires major sources of air pollutants to obtain and comply with an operating permit.
This graph shows the trend in the RSEI Score for air releases.
- The top chemicals by RSEI score for air releases were chromium and ethylene oxide.
- Stack air releases tend to contribute relatively less to the RSEI score than fugitive releases because chemicals released through stacks tend to get dispersed over a wider area than fugitive air releases, resulting in lower average concentrations.
- For a complete, step-by-step description of how RSEI models air releases and derives RSEI Scores from stack air emissions and fugitive air emissions, see “Section 5.3 Modeling Air Releases” in Chapter 5 (“Exposure and Population Modeling”) of EPA’s Risk-Screening Environmental Indicators (RSEI) Methodology, RSEI Version 2.3.6.
- For general information on how RSEI Scores are estimated, see Hazard and Potential Risk of TRI Chemicals.
This page was published in March 2019 and uses the 2017 TRI National Analysis dataset made public in TRI Explorer in October 2018.