### Question
How is the term lowest achievable emission rate defined?


### Answer
The term **lowest achievable emission rate** is defined in *42 U.S.C. § 7501* as the following:

> for any source, that rate of emissions which reflects—


(A) the most stringent emission limitation which is contained in the implementation plan of any State for such class or category of source, unless the owner or operator of the proposed source demonstrates that such limitations are not achievable, or


(B) the most stringent emission limitation which is achieved in practice by such class or category of source, whichever is more stringent

#### Citation:
  - *42 U.S.C. § 7501*
  - Heading: **CHAPTER 85-AIR POLLUTION PREVENTION AND CONTROL > SUBCHAPTER I-PROGRAMS AND ACTIVITIES > Part D-Plan Requirements for Nonattainment Areas > subpart 1-nonattainment areas in general**

