Worldwide on-road vehicle exhaust emissions study by remote sensing.

The remote sensing technology developed by the University of Denver provides the first practical approach to routinely characterize real-world, on-road automobile CO and HC exhaust emissions. It has been used to measure the exhaust emissions of more than 1 000 000 vehicles in many locations, This study presents an analysis and comparison of 22 fleet profiles collected by the remote sensor in different regions around the world. Three patterns of emissions distributions and contributions of the fleets are revealed by a hierarchial cluster analysis. The importance of vehicle maintenance on average CO and He emissions is revealed by a quintile analysis. Good maintenance practices in Gothenburg, Sweden, contrast with other locations such as Los Angeles, CA, and Melbourne, Australia. The absolute emissions differences between well- and badly maintained vehicles of any age are considerably larger than observable effects of emission control technology and vehicle age.