On-Road Remote Sensing of Automobile Emissions in the LaBrea Area: Year 2 (2003)

The University of Denver conducted a five-day remote sensing study in the LaBrea, California area in October of 2001.The remote sensor used in this study is capable of measuring the ratios of CO, HC, and NO to CO2 in motor vehicle exhaust.From these ratios, we calculate mass emissions per kg (or gallon) of fuel and the percent concentrations of CO, CO2, HC and NO in motor vehicle exhaust which would be observed by a tailpipe probe, corrected for water and any excess oxygen not involved in combustion.The system used in this study was also configured to determine the speed and acceleration of the vehicle, and was accompanied by a video system to record the license plate of the vehicle.Five days of fieldwork, October 15-19, 2001, were conducted as vehicles entered I-10 eastbound frontage road from LaBrea Blvd. in west Lost Angles basin.A database was compiled containing 26,975 records.Of these records the State of California provided make and model year information on 20,319 which contained valid measurements for at least CO and CO2, and most contained valid measurements for HC and NO as well.The database, as well as others compiled by the University of Denver, can be found at www.feat.biochem.du.edu .The mean percent CO, HC, and NO were determined to be 0.44%, 0.015%, and 0.041%, respectively.The emissions measurements in this study exhibit a gamma distribution, with the dirtiest 10% of the measurements responsible for 72.4%, 64.5%, and 56.7% of the CO, HC, and NO emissions, respectively.The HC readings contain a 21 ppm offset, which has been taken into account in all comparisons.The offset was determined by looking at the Model Year 2000 Ford vehicles.For the 1999 study, the Model Year 1999 Mercedes Benz vehicles that were used to estimate an offset of 17 ppm of HC.Appendix G shows an alternate offset calculation.This was the fourth year of a multi-year continuing study to characterize motor vehicle emissions and deterioration in the Los Angles area.However, because of the low traffic volumes and reconstruction at the Riverside site, a new ramp similar to the Denver and Chicago sites was used this year.The California Inspection and Maintenance Review Committee used this site and this instrument in 1999, and those data have been made available to E-23 and are included in this report.Vehicle emissions as a function of vehicle specific power revealed that NO emissions show a flat dependence on specific power when speed and acceleration are measured after emissions.HC emissions show a negative dependence on specific power -the expected trends.CO emissions show a slight positive dependence on specific power in the range from 5 to 30 kW/tonne.Using vehicle specific power, it was possible to adjust the emissions of the vehicle fleet measured in 2001 to match the vehicle driving patterns of the fleet measured in 1999.After doing so, it was seen that the emissions measured in the current year are lower than those measured during 1999.Model year adjustments gave equivocal results.Previously reported emissions data from Riverside, CA give almost identical results from the fleet.An analysis of high emitting vehicles showed that there is considerable overlap of CO and HC high emitters, for instance 4% of the measurements contribute 45% of the total CO and 38% of the total HC.The noise levels in the CO, HC and NO measurement channels were determined to be minimal compared to the standard error of the mean measurements.