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Airborne particulate matter (PM) in an urban atmosphere is a result of contribution from diverse range of source including domestic, industry and vehicles. PM emission is a matter a concern due to its multiple impacts on public health, air quality, and global climate. Ever increasing number of vehicles plying on the road is considered to be one of the major sources of PM. Particles in gasoline and diesel vehicle exhaust carry distinctive combinations of certain chemical compounds. Prominence of their chemical signature in ambient particulate matter can be considered as a direct indication of their relative importance as sources of emissions. In this study, Chemical speciation data of vehicle exhaust PM is analyzed and vehicle category wise distribution of carbon fractions is presented for different engine technologies and fuel types.

Variety of metals and elastomers/plastics are used in vehicle fuel systems. Though higher ethanol in gasoline can lead to efficient burning of fuel, material compatibility of non-metals is one of the major issues of concern. Material compatibility issue needs to be addressed before using higher contents of ethanol in gasoline because of reasons like permeation, swelling, leaching and plasticization, which lead to loss of material properties and subsequently resulting into field failures. For assessment of whether the fuel system will be able to perform as intended for its complete design life, it is necessary to know the impact of use of modified fuel on fuel system components. The impact on the in-use vehicles is particularly important in Indian context, where vehicles even more than 10 years old are plying. Most of the vehicles have not been designed for the 10% ethanol gasoline blend except for a few 4-wheelers.

A diverse range of sources like, domestic, industries and vehicles contribute to the airborne particulate matter observed in the urban atmosphere. Impact of growing number of vehicles, with a compounded annual growth rate of 15%, on air quality is evident. The particles in gasoline and diesel vehicle exhaust carry distinctive combinations of certain chemical compounds. The prominence of their chemical signature in ambient particulate matter is thus a qualitative but direct indication of gasoline and diesel vehicles' relative importance as sources of emissions. The vehicle emission profiles generated, by PM characterization together with the ambient particulate matter speciation data, could be a realistic input to the source apportionment study for identification of sources of air pollution.

The paper deals with methodology for selection of Emission Control Devices (ECD), test matrix and evaluation procedure followed for vehicles, engines and analysis of test results. In the present scenario, it is always being discussed that how existing vehicles and engines manufactured in India complying to Euro I /Euro II standard will perform with different sulphur percentage fuel. The emission control device such as Oxidation Catalytic Converter (OCC) is not very commonly used on the Euro-II vehicle and heavy-duty commercial vehicles. The performance of diesel oxidation catalyst on different sulphur percentage is of vital importance in Indian scenario. The particulate matter is always a concern in diesel vehicles and engines and most of Indian vehicles are having very low margin for particulate matter vis-à-vis regulation.