Natural gas combustion produces no significant aldehydes or other air toxins, which are a concern in gasoline and some other alternative fuels. The Clean Air Act of 1990 is a law designed to improve the air quality through the United States. Air quality levels in metropolitan areas across the country are monitored by the EPA who ranks cities according to the severity of their pollution. Areas of the country that exceed standards for pollutants are called non-attainment areas. NGVs can make significant contributions to Clean Air Act goals.
Natural gas is the cleanest burning alternative motor fuel commercially available today.
Emissions of non-methane organic gases and oxides of nitrogen can be up to 90 percent lower compared to gasoline vehicles. Dedicated NGVs also produce little or no evaporative emissions during fueling and use. Such emissions account for at least 50 percent of a gasoline vehicle's total hydrocarbon emissions. The Energy Policy Act was designed to establish a firm energy policy for the U.S. and to reduce our dependence on foreign oil. A significant portion of EPAct deals with alternative transportation fuels, requiring their use in certain fleets located in metropolitan areas with a 1980 population of 250,000 or more.