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In-use, light-duty vehicles were recruited in Cary, North Carolina for emissions testing on a transportable dynamometer in 1999. Two hundred forty-eight vehicles were tested in as received condition using the IM240 driving cycle. The study was conducted in two phases, a summer and winter phase, with half of the vehicles recruited during each phase. Regulated emissions, PM10, carbonaceous PM, aldehydes and ketones were measured for every test. PM2.5, individual volatile hydrocarbons, polycyclic aromatic hydrocarbons, sterane and hopane emissions were measured from a subset of the vehicles. Average light-duty gasoline PM10 emission rates increased from 6.5 mg/mi for 1993-97 vehicles to 53.8 mg/mi for the pre-1985 vehicles. The recruited fleet average, hot-stabilized IM240 PM10 emission rate for gasoline vehicles was 19.0 mg/mi.

As part of a multi-year program known as the ‘ECD Technology Validation Study’, which was conducted over the past few years (1999-2003) detailed data were obtained on the chemical characteristics of PM from diesel fueled trucks and buses operated with and without various after-treatment devices. This study has been conducted collaboratively by industry, federal, state and local government agencies, along with academic research institutions. Descriptive presentations of the results of the various phases of this study have been previously reported. The current study offers further insight into the data by investigating finer details of the association between the various chemical species and classes of compounds characterized. This paper provides an approach to such detailed analyses by using the chemical speciation data from the ECD Technology Validation Study (SAE2002-01-2873) as a case study.