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Why it Matters
As part of the Clean Air Act (CAA), EPA regulates Hazardous Air Pollutants (HAPs). HAPs include benzene, metals, and other pollutants that are known to cause cancer and other serious health effects. A facility is considered a major source if it has the potential to emit 10 tons per year of any one HAP or 25 tons per year of any combination of HAPs. All other facilities are considered area sources. Major sources, such as power plants and petroleum refineries, are subject to Maximum Available Control Technology (MACT) standards for regulated pollutants. MACT standards are stringent pollution control requirements based on the technology used in the best-controlled sources in the industry.
MACT standards significantly limit hazardous air pollutants, often reducing emissions to below the major source thresholds of 10 and 25 tons per year. For many years EPA’s policy has been that a major source remains a major source even after MACT is applied and it reduces its emissions. Sources must continue to operate under the more stringent requirements and maintain MACT-level low emissions.
A different approach – allowing the source to reclassify as an area source after it reduces its emissions below the threshold – would replace the source’s initial MACT requirements with less stringent requirements. The result could be a large increase in pollution. For example, after first applying the MACT, the source could switch to less effective pollution controls, or operate its controls less frequently or at lower removal efficiencies, and release more HAPs up to the major source threshold amounts. This increase could have significant health effects on local communities, especially those that are located near major sources of toxic air pollutants.
California alone has identified 42 sources of air pollution that are emitting below the 10 ton or 25 ton limits and would be eligible to reclassify and thus increase their pollution. This could mean up to 935 tons per year of additional toxic air pollution in California communities – this in the state that many consider as having the most stringent state standards. In other states where federal regulations are more likely to stand alone, the proportional increases could be even higher.
Allowing a major source to stop operating with stringent controls would be counter to the primary goal of the Clean Air Act of protecting public health and the environment by minimizing emissions consistent with standards such as MACT-based ones.
On Jan. 25, 2018, EPA issued guidance withdrawing the “Once In, Always In” policy and weakening the pollution control technology requirements for major sources of HAPs. On Oct. 1, 2020, EPA released a final rule replacing the “Once In, Always In” policy that allows major sources of HAPS to reclassify to area sources, making them subject to less stringent emissions control and compliance requirements. According to EPA, the rule could increase HAP emissions between 919 to 1,258 tons per year. Multiple groups have sued EPA challenging the final rule. On his first day in office, President Biden issued an Executive Order requiring EPA to review the final rule replacing the “Once In, Always In” policy.
In May 1995, The Environmental Protection Agency (EPA) issued “once in, always in” guidance for major sources under the Clean Air Act (CAA). This guidance declared that, prior to the first Maximum Available Control Technology (MACT) standard compliance date, a major source could be reclassified and not required to operate MACT if its potential to emit fell below the threshold amounts. After the first compliance date, a major source would no longer have this option and would be required to limit its Hazardous Air Pollutants (HAPs) emissions through MACT.
In 2007, EPA proposed a rule to replace the “Once In, Always In” guidance. EPA did not finalize this rule.
Jan. 25, 2018 EPA issues a guidance memorandum withdrawing the “Once In, Always In” policy. This new guidance establishes that, at any time, “a major source which takes an enforceable limit on its potential to emit and takes measures to bring its HAP emissions below the applicable threshold” may be reclassified and no longer be required to use MACT.
Feb. 8, 2018 The guidance is published in the Federal Register.
March 26, 2018 A coalition of environmental groups sues EPA in the D.C. Circuit over the guidance memo that weakens regulation of HAPs.
April 9, 2018 California sues EPA as well. The court later consolidates the cases as California Communities Against Toxics, et al v. EPA, Docket No. 18-1085.
Dec. 21, 2018 EPA states in its brief in California Communities Against Toxics v. EPA that the agency intends to conduct a notice and comment rulemaking to formalize the “Once In, Always In” guidance.
Feb. 19, 2019 The D.C. Circuit schedules oral argument for April 1, 2019 for California Communities Against Toxics, et al v. EPA, Docket No. 18-1085.
Feb. 25, 2019 EPA sends a draft proposed rule to formalize the “Once In, Always In” guidance memo to the Office of Information and Regulatory Affairs for review prior to publication in the Federal Register.
July 26, 2019EPA publishes a proposed rule to replace the “Once In, Always In” policy it withdrew in January 2018. This proposal formalizes the Jan. 2018 memo that allows a major source that falls below HAP emissions thresholds to reclassify and no longer use MACT. Comments may be submitted here until November 1, 2019.
Aug. 20, 2019 The D.C. Circuit finds that the January 2018 memo is not a final agency action and dismisses the case, California Communities Against Toxics, et al v. EPA, Docket No. 18-1085.
Oct. 4, 2019 California and environmental groups submit a petition for rehearing to the D.C. Circuit in California Communities Against Toxics, et al v. EPA, Docket No. 18-1085.
Jan. 22, 2020 The D.C. Circuit denies the petition for rehearing. California Communities Against Toxics, et al v. EPA, Docket No. 18-1085.
Oct. 1, 2020 EPA releases the final rule replacing the “Once In, Always In” policy. The final rule allows major sources of HAPS to reclassify to area sources, making them subject to less stringent emissions control and compliance requirements. According to EPA’s emissions impact analysis, the rule could increase HAP emissions between 919 to 1,258 tons per year. The rule will become effective 60 days after publication in the Federal Register.
Nov. 19, 2020 EPA publishes the final rule replacing the “Once In, Always In” policy in the Federal Register.
Jan. 15, 2021 Environmental groups file suit challenging the final rule. California Communities Against Toxics, et al. v. EPA, No. 20-1024 (DC Cir.).
Jan. 18, 2021 A coalition of environmental groups files a petition for reconsideration, arguing the final rule is arbitrary and capricious, and EPA acted unlawfully by removing existing regulatory requirements without public comment. The groups ask EPA to stay the rule for 90 days, withdraw the rule, and immediately withdraw associated guidance.
Jan. 19, 2021 A coalition of states file suit against EPA over the final rule. State of California, et al. v. EPA, No. 21-1034 (DC Cir.).