Controlling air pollution caused by engine emissions is at the top of the government's environmental agenda. In fact, local-government and private-sector fleets will soon be required to purchase alternative-fueled cars and trucks in an effort to reduce harmful emissions from fossil fuels — the leading source of air pollution in the United States. However, to control emissions, it is necessary to find alternative fuels that burn cleaner. Several fuels, such as compressed natural gas and methanol, have been suggested, but propane has shown the most promise and has become the number-one alternative motor fuel in the world. Tests conducted by the U.S. Environmental Protection Agency (EPA) show that propane vehicles can produce 30 percent to 90 percent less carbon monoxide and about 50 percent fewer toxins and other smog-producing emissions than gasoline engines. Recent tailpipe emissions tests done on the Orange County (California) Transit Authority's mass transit buses showed that propane's emissions are 87 percent lower in total hydrocarbons, 50 percent lower in nitrogen oxides, and 40 percent lower in particulate matter.* The reduction in engine emissions isn't the only benefit offered by propane. Because propane is contained in a sealed, pressure-tight system at all times, there are no evaporative emissions as there are with gasoline. This eliminates a significant source of secondary pollution. * Source: National Propane Gas Association/Propane Education & Research Council, February, 2000. PROPANE EDUCATION & RESEARCH COUNCIL