Voluntary is the operative word, and it bites for a structural reason. The Clean Air Act currently requires facilities classed as minor polluters to disclose their emissions through state agencies, and the proposal would hand that decision to state and local officials instead [2]. Do the arithmetic on the Northern Virginia fleet and the average generator comes out around 2.6 megawatts [17], small enough on its own that no single permit invites the scrutiny the aggregate would.
Nitrogen oxides are the headline worry because they form ground-level ozone, but the same sites also emit carbon monoxide and heavy metals, and between them produce all six criteria pollutants the EPA ties to asthma, heart disease, and cancer [6]. Without a disclosure duty, a resident cannot establish what is actually in the air, and that record is the first thing any legal challenge or neighbourhood campaign needs [8].
Jeremy Fisher, a senior adviser at the Sierra Club, said the plan "opens the door to silence communities concerned about pollution" [7]. Joe Goffman, a former EPA assistant administrator, framed it as a message to those communities: "you all may have thought this was an ironclad promise, but it no longer is" [9].
The proposal does not arrive alone. It sits with a Clean Air Act resource page the agency has published for data centre developers under administrator Lee Zeldin, whose stated aim is to make the United States the AI capital of the world [11].
Europe restricts data centres on different terms: Brussels has told Big Tech to align with climate goals or stay away, Denmark has paused grid connections, and Spain is drafting rules tying grid access to hourly renewable matching [14]. Its binding constraint has been electricity and water; the American one is local air quality, largely because US sites lean far harder on on-site diesel to cover gaps in the grid [15]. That difference is why the change reaches past the states it names.
