### Question
How is the term modification defined?


### Answer
The term **modification** is defined in *42 U.S.C. § 7411* as the following:

> any physical change in, or change in the method of operation of, a stationary source which increases the amount of any air pollutant emitted by such source or which results in the emission of any air pollutant not previously emitted

#### Citation:
  - *42 U.S.C. § 7411*
  - Heading: **SUBCHAPTER I-PROGRAMS AND ACTIVITIES > Subchapter Referred to in Other Sections > Amendments**

