### Question
How does the law define existing source?


### Answer
Under *42 U.S.C. § 7412*, **existing source** is defined as:

> any stationary source other than a new source

#### Citation:
  - *42 U.S.C. § 7412*
  - Heading: **CHAPTER 83-ENERGY EXTENSION SERVICE > SUBCHAPTER I-PROGRAMS AND ACTIVITIES > Part A-Air Quality and Emission Limitations**

