Once In Always In Guidance for Major Sources under the Clean Air Act - Environmental and Energy Law Program – Harvard Law School
New guidance under the Clean Air Act clarifies that once a facility is classified as a major source of emissions, it remains so indefinitely, impacting compliance obligations.
Aforeworn detected this change in the Environmental & Emissions Compliance (EPA) space on September 2, 2026 and published this briefing so affected operators are forewarned rather than caught off guard. It is rated High urgency. All major source operators under the Clean Air Act, including manufacturers, power generators, and chemical processors. should confirm how it applies to their specific situation before acting. There is a time constraint attached: Immediate review and compliance adjustments as necessary.. Acting after that point can mean penalties, a lapsed licence, or lost eligibility — exactly the kind of surprise Aforeworn exists to prevent. Aforeworn monitors Environmental & Emissions Compliance (EPA) continuously and turns every detected change into a plain-English briefing like this one, so you always know first. Forewarned is forearmed.
What changed
The 'Once In Always In' policy means facilities classified as major sources cannot revert to minor source status, affecting emissions reporting and compliance requirements.
Who it affects
All major source operators under the Clean Air Act, including manufacturers, power generators, and chemical processors.
What you must do
Review current emissions classifications and ensure compliance with major source regulations.
Deadline
Immediate review and compliance adjustments as necessary.
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Aforeworn watches Environmental & Emissions Compliance (EPA) around the clock and alerts you the moment a rule moves — with a plain-English brief on what to do.
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