The Jan. 25, 2018, U.S. Environmental Protection Agency (EPA) memorandum on “Reclassification of Major Sources as Area Sources” significantly changes an EPA air quality and compliance policy in place since 1995.

This “once-in, always-in” environmental compliance policy mandated that if a source ever exceeded the major source threshold for hazardous air pollutants (HAP), the facility would permanently be classified as major, regardless of any pollution reduction activities. (The major source threshold is 10 tons per year (tpy) of any single HAP or 25 tpy of any combination of HAP. A non-major source is known as an “area” source.) This new policy only affects sources classified as “major” for HAPs.

The revised policy states that major sources can be reclassified as area sources at any time, provided the facility limits its potential to emit below major source air quality thresholds.

Why is this important?

Example 1

A facility operates several painting booths. For three months a decade ago, its 12-month rolling HAPs exceeded 10 tpy of toluene, a HAP. This classified the facility as a major HAP source and made it subject to a specific National Emission Standards for Hazardous Air Pollutants (NESHAP). It has since reformulated to a lower HAP paint and substantially reduced production due to jobs moving to Mexico. The actual HAPs are now around 1 tpy of toluene. But under “once-in, always-in,” the facility is still subject to the NESHAP and couldn’t get a permit mandating it stays under the 10/25 tpy major source threshold to be released from the NESHAP. After this memo, the facility can be released and get a permit limit of 10/25 tpy. This eliminates the NESHAP recordkeeping and risk of noncompliance.

Example 2

A coal-fired boiler was repowered to burn only natural gas. Combusting coal, the boiler was a major HAP source and subject to a NESHAP. Burning natural gas, emissions are well below 10/25 tpy. Under new policy, the facility can request a state limit of 10/25 tpy and no longer be subject to NESHAP compliance requirements that were only relevant when burning coal.

Much has been made in the media that this policy will lead to an increase in HAP emissions; however, the policy does not prevent an area source that increases its emissions from becoming a major source and thus required to comply with NESHAP standards. Facilities will have to maintain emissions within area source levels. The 1995 policy interpreted the actual regulatory language; the law itself was never changed to codify “once-in, always-in.” This 2018 policy reverts NESHAP implementation back to the plain-language reading of the statute.


Are you a once-in, always-in source? Burns & McDonnell’s air permitting engineers can help you reduce your regulatory risk with an area source limiting permit. Learn more about how we can assist with air quality and compliance projects.


Robynn is an associate environmental engineer at Burns & McDonnell with nearly 25 years of experience. Throughout her career, she has worked with industrial and utility clients to help acquire operating and construction air permits for projects.