Journal of Earth Sciences and Geotechnical Engineering

Light-Duty Vehicle Emissions and Urban Air Quality: Past, Present, and Future Perspectives

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• Abstract

  A perspective on past, present, and future light-duty vehicle emissions and urban air quality is provided. In conjunction with engine advancements, automotive fuel composition has been fine tuned to balance efficiency and power demands while minimizing emissions. Pollutant emissions from internal combustion engines result from complex processes involving interactions between the fuel and engine parameters. Engine hardware and operating conditions, after-treatment catalysts, and fuel composition all affect the amount and composition of emissions leaving the vehicle tailpipe. While engine and after-treatment effects are generally larger than fuel effects, engine and after-treatment hardware can require specific fuel properties. Consequently, the best prospects for achieving the highest efficiency and lowest emissions lie with optimizing the entire fuel–engine–after-treatment system. Vehicle emissions consist of volatile organic compounds (VOCs), CO, nitrogen oxides (NOx), and particulate matter (PM). VOCs, NOx, and PM contribute to photochemical smog in urban atmospheres. The past few decades have seen large reductions in the emissions of NOx, VOCs, and particulate matter (PM) emissions from new vehicles. This reduction of emissions from traffic has been an important factor in improvements in the air quality in many U.S. and European cities.