H.R.161

Clarifies when a change in a stationary source constitutes a modification or construction under the Clean Air Act.

Amends sections 111, 169, and 171 of the Clean Air Act to clarify when a physical change in, or change in the method of operation of, a stationary source constitutes a modification or construction. Defines "modification" to exclude changes that do not result in a significant emissions increase. Requires permits for construction involving physical construction of the discrete parts of an emissions unit at a major emitting facility.