### Question
How is the "retrofit technology" defined?


### Answer
The term **retrofit technology** is defined in *42 U.S.C. § 16091* as follows -

> a particulate filter or other emissions control equipment that is verified or certified by the Administrator or the California Air Resources Board as an effective emission reduction technology when installed on an existing school bus

#### Citation:
  - *42 U.S.C. § 16091*
  - Heading: **CHAPTER 149-NATIONAL ENERGY POLICY AND PROGRAMS > SUBCHAPTER VII-VEHICLES AND FUELS > Part C-Clean School Buses**

