On the recordJuly 11, 1995
It is maximum achievable controlled technology, which is not stated in parts per million. There are other standards. For example, there are radiation standards that do specify so many rems or millirems per year, et cetera. The Clean Air Act is maximum achievable controlled technology. That gives to the administrator a broad discretion as to what is maximum and what is achievable; that is to say, what is on the shelf.
Source
govinfo.gov




