Detection of Gasoline Vehicles with Gross PM Emissions 2007-01-1113

Light duty gasoline vehicles (LDGV) are estimated to contribute 40% of the total on-road mobile source tailpipe emissions of particulate matter (PM) in California. While considerable efforts have been made to reduce toxic diesel PM emissions going into the future, less emphasis has been placed on PM from LDGVs. The goals of this work were to characterize a small fleet of visibly smoking and high PM emitting LDGVs, to explore the potential PM-reduction benefits of Smog Check and of repairs, and to examine remote sensing devices (RSD) as a potential method for identifying high PM emitters in the in-use fleet.

For this study, we recruited a fleet of eight vehicles covering a spectrum of PM emission levels. PM and criteria pollutant emissions were quantified on a dynamometer and CVS dilution tunnel system over the Unified Cycle using standard methods and real time PM instruments. The vehicles were then tested using RSD equipment over a test track, tested with a standard Smog Check, and tested with a screening device during the Smog Check. The PM emission rates of the visibly smoking vehicles range from 60 to 1718 mg/mi over the UC cycle. The light or invisible smokers had PM emissions ranging from 7 to 25 mg/mi. The smoking vehicles showed particle number rates on the order of 10¹³∼10¹⁴ particles/mi, which are 10∼1000 times higher than typical FTP particle number emission rates for modern low emitting gasoline vehicles. Vehicles that had higher emission rates over the UC tests generally showed higher emissions as measured by RSD systems for the gaseous species. The relationship or scale factor between RSD PM emissions and filter mass emissions is different for each RSD method and wavelength, and also appears to be different for black smoke than blue smoke. The effects of repairs have not yet been assessed.