### Question
How does the law define greenhouse gas?


### Answer
Under *42 U.S.C. § 7545*, **greenhouse gas** is defined as:

> carbon dioxide, hydrofluorocarbons, methane, nitrous oxide, perfluorocarbons,[9](#7545_9_target) sulfur hexafluoride

#### Citation:
  - *42 U.S.C. § 7545*
  - Heading: **CHAPTER 85-AIR POLLUTION PREVENTION AND CONTROL > SUBCHAPTER II-EMISSION STANDARDS FOR MOVING SOURCES > Part A-Motor Vehicle Emission and Fuel Standards**

