I'm mixing things. Airports actually are heavily regulated by the federal government and are subject to federal laws, the Aeronautics Act and so forth. Just like many other facilities, they can be shipping hazardous goods, and because they've got a lot of fuel and so forth being stored, utilized, and spilled, they're watched very closely.
On the question of whether or not they require environmental impact assessments, that's a really good question. I'm sorry I can't answer off the top of my head. Probably under the law they do, but they could be simply required to do a simple...I forget the first stage.