Review Article: Transportation Control Measures for Air Pollution Reduction in Greater Cairo
*Hassan, S. K. M.
Air Pollution Department, Environmental Research Division, National Research Centre
Economic growth and urban development is normally associated with pressing need for transport. When public transport cannot support such development an increased demand on private cars is usually the result. The fossil fuels related pollution has been recently aggravated by the rapid development and urbanization. Tailpipe emissions usually include hydrocarbons (HC) (totally/partly burned fuel), NOx (reaction of air nitrogen with oxygen in the high pressure conditions of the engines to give Nitrogen Oxides), carbon monoxide (CO) and carbon dioxide (CO2). Traffic–related primary PM emissions may also include elemental carbon (EC), organic compounds (OC), and re-suspended dust and heavy metals from braking and general vehicles wearing processes The stages through which automobile emissions can be controlled may be : pre-combustion stage in which fuel quality can be optimized, combustion stage where engines could be modified, and post-combustion stage where exhaust could be catalytically converted to more benign constituents. Policies and regulations can thus be directed toward any of these stages and can aim at either producers or dealers. Non-technical ways such as behavioral adaptations in the mode of transport and frequency of cars maintenance can also be applied. Moreover, governments can enforce vehicle emission control policies such as: 1- Phasing out leaded gasoline which was proven effective in reducing lead emissions, 2-Adoption of hydrogen fuel cell vehicles as an alternative to gasoline fueled ones was also suggested to reduce major pollutants and greenhouse gases emissions ,3- Compressed natural gas (CNG) engines emit significantly lower levels of CO, TSP, NOx and SO2,4- Liquefied petroleum gas (LPG) usage in taxis and buses instead of diesel was also found to substantially reduce the emissions of NOx and respirable suspended particulates (RSPs) .So, there is a pressing need to promote CNG, LNG, and other clean alternative fuels used in public transport, and to promote the use of clean energy vehicles like the hybrid cars through preferential policies.