Introduction: Air pollution can be defined as the harmful gases present in the air we breathe. Pollution can be caused by natural sources or result from human activities. Natural pollutants include: dust, pollen, wildfire smoke, and bacterial and volcanic action. However, human activities are the main cause of air pollution. The main sources of air pollution are industry (factories and power plants) at 36% and road transport at 26%. Currently, the number of vehicles on the roads continues to increase, which leads to increased production of pollutants. The most common pollutants in transportation are nitrogen oxides, carbon monoxide, sulfur dioxide, hydrocarbons and particulate matter. This essay will examine the impacts on human health, the environment and even the economy that result from these pollutants. It will then evaluate some of the solutions proposed to reduce these harmful emissions. The increase in the number of vehicles The situation is that the growth in the world's population, with the new styles of vehicles that have been produced, is the main cause of the increase in the number of vehicles in the world. In the United States, for example, automobiles have become synonymous with freedom of life and culture, leading wealthy households to want to own at least two cars (Mondt, 2000). In Britain, as another example, the number of vehicles increased in 2004 to 29 million vehicles, including 24 million passenger cars. Most people use their own cars for short trips, which creates unnecessary pollution. As a result, the amount of vehicle emissions has increased with the growth of the population and the number of cars. Air pollution is not a recent problem and was recognized as early as 1966, according to...... middle of article......Works CitedFaiz, A., Weaver, C., S ., and Walsh, M. , P. (1996) Air pollution from motor vehicles: standards and emission control technologies. Washington, DC: World Bank OEE (2006) Energy Consumption Data Handbook. Natural Resources CanadaMondt, J., R. (2000) Cleaner Cars: The History and Technology of Emission Controls Since the 1960s. Warrendale, USA: SAE InternationalPimentel, D. (2007) Pollution is the cause of 40% of deaths worldwide. SciencedailySAE (1994) Developments in alternative fuel technology. Warrendale, United States: SAE internationalFuel Economy, Environmental Protection Agency, United States (www.fueleconomy.gov).How stuff works (www.howstuffworks.com).Ministry of the Environment (Environment Canada), Government of Colombia -British, Canada (www .env.gov.bc.ca) (2001).Waltham Forest, Great Britain (www.walthamforest.gov.uk).