Transportation

Fossil Fuels

Each one of these means of transportation runs on fossil fuels of crude oil distillates and coal, apart from modern train systems in developed countries, which may run on automated power. These fuels are subjected to internal cycles of combustion, giving gaseous by-products of carbon dioxide (CO2), carbon monoxide, and sulphur dioxide. Methane and nitrous oxide are also emitted by cars. World over, the greenhouse gas contribution of transportation is very high as a result of factors that include an increase in the number of vehicles, volume of passengers, and freight traffic. The percentage contribution of CO2 from transportation alone varies from state to state and country to country. In 1990, Japan's contribution was put at about 19 percent, and that of the United States surprisingly doubled between 1960 and 2001. Specifically, it is reported that emissions of CO2 in the United States jumped from 2 billion metric tons in 1960 to almost 5.7 billion metric tons in 2001, accounting for over a 100 percent increase, with over 20 percent of this emission linked to transportation. Transportation is also reported to account for 40 percent of volatile organic compounds, 77 percent of carbon monoxide, and 49 percent of nitrogen oxide emissions in the United States. In Canada, also, it is reported that transportation is the largest single anthropogenic source of outdoor air pollution. On average, each of the several million vehicles registered across the country emits approximately 5 tons of air pollutants and gases annually. This trend in record is the same for all industrialized nations and several developing nations, such as Nigeria in West Africa, because of an increased population and a rapid rate of economic growth, bringing about increased use of automobiles and other means of transportation. This increase has brought with it increasing emissions of air pollutants and greenhouse gases because of the type of engines in use and the nature of the fuels in place.

In general, it is reported that combustion engines emit nitrogen oxides (NOx), carbon monoxide, and unburned hydrocarbons capable of chemical transformation in the atmosphere, creating other gaseous matter such as ozone. Ozone is a triatomic molecule consisting of three atoms of oxygen; it is an allo-trope of oxygen but is much less stable. Its instability makes it a strong oxidizing agent, having the ability to decompose to oxygen in the atmosphere within 30 minutes. In its physical undiluted state, at standard temperature and pressure, it is a pale blue, odorless gas. In the troposphere, ozone acts as a greenhouse gas and has a radiative forcing of about 25 percent that of CO2. Around the Earths surface, it poses a regional air pollution problem damaging human health and agricultural crops.

...