Regulatory Update: EPA Withdraws OIAI Air Toxics Policy

Based on the 2014 National Emissions Inventory, there are 2,594 major sources of hazardous air pollutants (HAPs) in the contiguous United States. Following the EPA’s withdrawal of the 23-year old policy referred to as the “Once In, Always In” (OIAI) Policy, many of these facilities may want to reevaluate whether their emissions meet the “major” thresholds with the possibility of avoiding onerous compliance requirements and cost burdens—because once in doesn’t mean always in anymore.

The OIAI Policy, which required that a major source of air pollution always be classified as a major source, was officially rolled back by the EPA at the end of January. Without this regulation, major sources—facilities that have the potential to emit 10 tons per year (tpy) of any single HAP or 25 tpy of any combination of HAPs—may be re-classified as a non-major or area source after reducing their emissions below this threshold.

Removing regulatory burden from once-major sources

Under the 1995 OIAI Policy major sources were allowed to avoid being subject to their respective Maximum Achievable Control Technology (MACT) standards by accepting an enforceable limit below the major source threshold as long as the limit was in place before the first substantive compliance date which, in most cases, was back in the 1990s. After that first compliance date, any existing major source subject to the MACT standard would remain permanently subject even if future reductions brought emissions below that threshold. Now, without the OIAI policy, facilities that weren’t able to cap emissions before the first compliance date can do so and avoid regulation under the applicable MACT standards, including the associated testing, monitoring, recordkeeping, reporting, and Title V permitting requirements. While this change in policy will relieve a regulatory burden for some facilities, the potential air quality implications are unknown. At this point, it’s unclear whether emissions from facilities no longer subject to MACT standards will increase to the point of compromising the effectiveness of the program.

Map developed by in-house air modeling expert Matt Jones shows how these sources are distributed geographically across the US.

Potential impacts to control equipment usage

Since 1990, EPA has adopted MACT standards for approximately 100 major source categories and 70 area source categories. These standards regulate nearly 200 pollutants emitted from sources ranging from aerospace, surface coating, pharmaceutical production, and chemical manufacturing facilities to chrome plating process units, boilers, engines, and turbines. Each MACT standard is specific to that category’s operations, but for many source categories the standards require a reduction in HAP emissions of 95% or more, which is often achieved by employing highly efficient and costly emission control equipment.

In light of this regulatory change, facilities that can cap emissions below the major source threshold may be able to remove control equipment or operate it at a lower control efficiency (and therefore save on operational costs like fuel). For example, a facility that installed a thermal oxidizer to achieve 95% control of HAP emissions may now cap emissions below the regulatory threshold and then run the oxidizer at a lower temperature and achieve only 85% instead of 95% control, resulting in an increase in emissions. Further, in cases where facilities can limit operations or production such that their HAP emissions without emission controls remain below the 10/25 tpy threshold, it may be possible to remove their control equipment altogether.

However, facilities will need to consider other applicable regulations to determine whether control equipment removal or operational changes are an option, as many states have minor source permitting and air toxics programs in addition to other applicable EPA regulations that may prohibit such changes. The potential implications of this policy change can’t be evaluated without understanding better which sources will seek area source status and how other state or federal regulations may limit the operational changes they can make.

Facilities currently designated as major sources subject to MACT standards should carefully review their potential emissions calculations, historical emission records, and applicable operating permit requirements to evaluate whether they can take advantage of this policy change. Even in cases where emission controls will remain in place and continue to be operated in the same way, there could be substantial regulatory relief associated with reduced recordkeeping, reporting, and Title V permitting requirements. We on the air services team are closely following developments and can assist our clients, on a case-by-case basis, to define appropriate options and provide guidance in implementing the new once-in, not-always-in policy to achieve the most economical and efficient solutions for their HAP emission sources while maintaining compliance with the applicable standards and regulations.


Kelley Begin Practice Leader Air Services

View All Posts

Scroll back to top of the page