Clean Air Act Amendments of 1990

The Clean Air Act Amendments of 1990 expanded provisions to control ground-level ozone (urban smog), carbon monoxide, and particulate emissions from vehicles.The amendments, which build on recommendations in the original Clean Air Act that encouraged the use of alternative fuels such as propane, place increased focus on eliminating the use of ozone-depleting substances.


In response to the CAAA, the Environmental Protection Agency developed the Clean Fuel Fleet Program to enforce stricter limitations on vehicle pollution. The program requires that a percentage of new cars and light- and medium-duty trucks purchased by certain fleets meet lower hydocarbon and nitrogen oxide emission standards.

In 1998, 30 percent of new vehicles purchased by centrally fueled fleets in selected cities were required to use clean fuels and meet tailpipe emissions standards that were lower than those in place for general passenger cars; this requirement increased to 70 percent by the year 2000. The program affects 22 ozone and carbon monoxide nonattainment metropolitan areas in 19 states across the country.

For more information, visit the Alternative Fuels and Advanced Vehicles Data Center’s 1990 Clean Air Act Amendments page. 

Propane Refueling

Infrastructure Map

Propane Refuelling Map   

Fleet Process Conversion Overview

Use a Conversion Partner to convert your fleet. Download List of EPA/CARB- Certified list of Propane Autogas Vehicles.