here's something more local and what i would expect. However, it's murky [link at the bottom]

"Mississippi officials told xAI it could run the generators without an air permit because they were deemed “temporary” and “mobile” units.". Makes sense because as far as i can tell they were on trailers.

but then there's this: "But lawyers at the Southern Environmental Law Center, representing the NAACP in the federal lawsuit, have long maintained that such a loophole doesn’t exist, and that running such turbines without a permit violates the federal Clean Air Act.

“Mobile, temporary, portable, whatever you want to call them, turbines need air permits,” Patrick Anderson, a center attorney, told Mississippi Today."

as per typical, it's not clear who's right

https://mississippitoday.org/2026/04/15/data-center-turbines...