EPA Abandons Once-In-Always-In Clean Air Act Policy

Posted on 11/13/2020 by Roger Marks

Update 11/19/20: EPA's Final Rule to allow major sources of hazardous air pollutants (HAP) to be reclassified as area sources following a sufficient decrease in potential to emit (PTE) appeared in the Federal Register today. 

The Final Rule is effective January 19, 2021. 

EPA will officially abandon its longstanding Once-In-Always-In policy for major sources of air pollution under the Clean Air Act.

Under a new Rule, a facility that reduces its potential to emit hazardous air pollutants (HAP) below the major source thresholds can be reclassified as an “area source.” The rule amends the General Provisions of the National Emissions Standards for Hazardous Air Pollutants (NESHAP) and implements a “plan language reading” of the definitions for "major source" and "area source" in Section 112 of the Clean Air Act.

NESHAP require facilities to apply specific technologies and controls to specific equipment to keep HAP emissions below EPA thresholds. 

Reversing the Once-In-Always-In policy provides a new incentive for facilities to reduce air pollution.

In addition to reversing the once-in-always-in policy, the Rule:
  • Finalizes changes to clarify compliance dates, notification and recordkeeping requirements; and
  • Adds an electronic reporting requirement  
Lion will update this post when the rule is published to the Federal Register and an effective date is available. 

Clean Air Act Major Source vs. Area Source 

The Clean Air Act defines a major source of air pollution as a facility that emits:
  • 10 tons per year (tpy) of any single HAP; or
  • 25 tpy of any combination of HAP
An area source is any source of air pollution that is not a major source.

Major sources are subject to more stringent requirements for controlling air pollution, including Maximum Achievable Control Technology or MACT standards. The requirements for area sources are less stringent, allowing for the use of Generally Available Control Technology (GACT), which are typically less expensive than MACT.

Until a 2018 memo, EPA policy stated that a major source of air pollution remains a major source even if it reduces its potential to emit below the major source threshold (i.e., Once-In-Always-In).

Under the new Rule, which effectively codifies the 2018 memo, a facility that reduces its potential to emit hazardous air pollutants (HAP) below the major source thresholds can be reclassified as an area source if it reduces its potential to emit, or PTE, below the major source threshold levels.

in June 2020, EPA added 1-bromopropane to the list of Hazardous Air Pollutants (HAP), the first addition to the list in three decades. 

Last of 2020! Complete EPA Regulations Training | Dec. 2–3

This unique two-day webinar will get you up to speed on new and changing US EPA air, water, and chemical regulations you must know to maintain compliance in 2021.  
  • EPA's new Waters of the US (WOTUS) Rule
  • Major Lautenberg Law amendments to TSCA
  • CSB's new chemical release reporting rule 
  • The latest Clean Air Act requirements for facilities 
Join a Lion instructor live on December 2–3 to get a strong handle on the EPA requirements that impact your facility, how these programs fit together, and what you must do to comply. 
Or learn at your own pace with these two easy-to-use online courses: 
Complete Environmental Regulations Online Course
Clean Air Act Regulations Online Course 

Tags: Clean Air Act, MACT, new rules

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