Characterization of large fleets of vehicle exhaust emissions in middle Taiwan by remote sensing.

Measurement of fleet emissions by means of remote sensing was conducted in middle Taiwan and the distributions and governing factors were characterized and examined. Results show the type of sampling sites is a dominant factor for the emission levels, and driving speeds and accelerations of the vehicles. In this study, the mean CO, HC, and NO concentrations at the urban and rural sites are apparently higher. The quantitative relationship between the pollutant concentration and mean speed or acceleration was established. Analysis of effect of the vehicle model year on the average fleet emissions was also conducted. It indicates those relatively older vehicles are higher emitters and contribute significantly more to total fleet emissions. On the other hand, the variation trends with model year are independent of the site characteristics and the effect of vehicle age on CO, HC, and NO emission is similar.