### Question
What is the definition of ultra-low sulfur diesel fuel?


### Answer
The definition of **ultra-low sulfur diesel fuel** is as follows in *42 U.S.C. § 16091a*:

> diesel fuel that contains sulfur at not more than 15 parts per million

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

