A zero-emission vehicle is a road, rail or other vehicle that does not emit exhaust gasses or other harmful substances from its onboard source of power.
Road vehicles are one of the leading sources of both greenhouse gasses and toxic emissions that are resulting in hundreds of thousands of premature deaths annually. Among these emissions are carbon monoxide, hydrocarbons, ozone, lead, various oxides of nitrogen, volatile organic compounds, 1,3-butadiene and ultra-fine particulate matter.
Replacing conventional, internal combustion vehicles with zero-emission vehicles, such as those powered by batteries or fuel cells, could be an important step in reducing environmental deterioration and improving public health. However, it is important to keep in mind that this would eliminate only part of the pollution caused by road and other vehicles. In fact, it is possible that the emissions that do not come from the operation of the engines themselves are as large as, or even greater than, those that come directly from the engines.
A broader, and perhaps more useful, definition of zero-emissions vehicles would also include any additional emissions resulting from the production, use, and ultimate disposal of the vehicle, including the mining and processing of the metals, plastics and electronic devices used in them, the emissions resulting from the production and distribution of the electricity or other fuel used in the vehicle, and the not insubstantial toxic runoff from tire, road and brake pad abrasion.