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A comparative analysis was made on the emissions from a 2004 and a 2007 heavy-duty diesel engine to determine how new engine and emissions technologies have affected the chemical compounds found in the exhaust gases. Representative samples were collected from a source dilution sampling system and analyzed for both criteria and unregulated gaseous and particulate emissions. Results have shown that the 2007 regulations compliant engine and emissions technology not only reduced the specifically regulated exhaust pollutants, but also significantly reduced the majority of unregulated chemical species. It is believed that these reductions were achieved through the use of engine optimization, aftertreatment system integration, and ultra-low sulfur diesel fuel.

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.