The Clean Air Act, as enacted by Congress, requires states with "nonattainment" (dirty air) areas to establish a permit program that regulates "new or modified major stationary sources" of air pollution." Under EPA regulations, a state could allow a plant with multiple sources of pollution to be treated as one source of pollution. That is, the industrial facility would be treated as if it were under a "bubble." The pollution emitted by the facility under the bubble would be measured, rather than measuring emission from each component within the bubble.
The National Resources Defense Council (NRDC) challenged the EPA "bubble rule" as inconsistent with the Clean Air Act. The Court of Appeals overturned the EPA regulation. That decision was appealed.

1. Congress did not specify that the EPA could use a "bubble" in measuring pollution emitted from an industrial facility, so why can EPA come up with such an idea?
2. If the courts did not grant such deference to agencies, what would be the practical result?