Assessment of Particulate Matter Emissions from a Sample of In-Use ULEV and SULEV Vehicles 2006-01-1076

Vehicles that meet the Federal Tier II and the California LEV II Vehicle Standards (e.g. ULEV and SULEV) are a rapidly growing percentage of the fleet. Sales weighted fleet average emissions of new vehicles are already below the LEV certification levels and should be below ULEV certification levels within two years. ULEV and SULEV vehicles represent the “typical” vehicle future for the next decade or two. Data on particulate emissions from these vehicles are currently very limited.

In this study, emission tests using the standard Federal Test Procedure (FTP) were conducted on a small in-use vehicle fleet of ULEV and SULEV vehicles to determine their particulate matter mass emission rates, chemical compositions, particle numbers, and particle size distributions. Particulate sampling utilized Teflon filters for mass determination and quartz filters + PUF-XAD cartridges for chemical speciation. Each bag of the test was sampled separately. Each filter and cartridge was collected cumulatively over all the tests from the same vehicle category. Particle number was measured with a condensation particle counter (CPC) and size distribution was measured with a fast scan particle sizer. A thermodenuder was equipped to the CVS sampling tunnel so that either all or only non-volatile particles were measured. At the low emission levels from these vehicles, it is important to carefully characterize the background. To do this, separate bags of the tunnel blank (background) measurements were taken each day over the full FTP cycle.

The available results from our study will be presented in this paper. The issues regarding measuring the particulates at extremely low level will be discussed as well.