Air Releases

This graph shows the 10-year trend in the quantity of chemicals released into the air. EPA regulates air emissions under the Clean Air Act. Facilities must comply with permitting requirements if they meet certain criteria such as pollutant releases above specified thresholds.

From 2013 to 2022:

• Releases into the air decreased by 26% (-204 million pounds).
• Air releases of hydrochloric acid, sulfuric acid, hydrogen fluoride, methanol, and toluene decreased the most.
• The decrease in air releases was driven by reduced releases of hydrochloric acid and sulfuric acid to air from electric utilities due to: a shift from coal to other fuel sources (e.g., natural gas); and the installation of pollution 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. Electric utilities that use only fuels other than coal or oil (such as natural gas) are not required to report to TRI. More information about this sector is available in the Electric Utilities sector profile.
• Air releases of chemicals classified as carcinogens by the Occupational Safety and Health Administration (OSHA) increased; see the Air Releases of OSHA Carcinogens figure.
• For trends in air releases of chemicals of special concern, including lead and mercury, see the Chemical Profiles section.

In 2022:

• The TRI chemicals released into the air in the largest quantities were ammonia and methanol.
• Air releases of TRI chemicals decreased by 1% since 2021.
• Air releases from the paper manufacturing, primary metals manufacturing, and chemical manufacturing sectors drove the decrease. For 2022, TRI reporting requirements were expanded to include additional natural gas processing facilities; air releases from these newly-covered facilities partially offset the decrease in air releases from other sectors.

This graph shows the 10-year trend in RSEI Scores for TRI air releases.

• The chemicals that contributed the most to the RSEI Score values for air releases were chromium and ethylene oxide.
  • While the combined quantities of chromium and ethylene oxide released to air accounted for less than one percent of total air releases in 2022, they accounted for 30% and 27% of total RSEI Score, respectively.
• The increase in score for air releases from 2020 to 2022 is due in part to increases in releases of ethylene oxide, nickel, and cobalt compounds.
• As shown in the “Pounds Released” chart, facilities reported considerably more stack air emissions than fugitive air emissions, but their relative contributions to the RSEI Score values have been similar in recent years, as shown in the “RSEI Score” chart. This is because chemicals released through stacks tend to be dispersed over a wider area than fugitive air emissions, resulting in lower average concentrations in the environment. As a result, surrounding populations are less likely to be exposed to chemicals released through stacks compared to fugitive emissions like leaks from equipment or releases from building ventilation systems.
• For a complete step-by-step description of how EPA’s RSEI model derives RSEI Score values from stack air emissions and fugitive air emissions, see “Section 5.3: Modeling Air Releases” of EPA’s Risk-Screening Environmental Indicators (RSEI) Methodology.
• For general information on how RSEI Scores are derived, see Potential Risks from TRI Chemicals.