EPA proposed revisions to its New Source Review (NSR) air permitting regulations, which would distinguish between construction of a stationary source and construction of non-emitting components or structures for a future covered source, while codifying that the latter can occur before an owner or operator obtains an NSR air permit for a new major stationary source or major modification. EPA’s proposed revisions would change its policy from requiring a permit to begin any construction that is of a permanent nature or costly, to requiring a permit to begin only construction of components or equipment that emit air pollution.