Real-World Vehicle Emissions: A Summary of the Eighth Coordinating Research Council On-Road Vehicle Emissions Workshop

Abstract

The Coordinating Research Council (CRC) has sponsored a series of workshops over the last decade focusing on the most recent real-world vehicle emissions research. This summary presents findings from the eighth CRC-sponsored workshop from researchers who are engaged in improving our understanding of the contribution of mobile sources to air quality. Participants in the workshop discussed efforts to evaluate and improve mobile source emission models, field programs designed to understand the contribution of mobile sources to emission inventories, results from gas-and particle-phase emissions studies from spark-ignition and diesel-powered vehicles, as well as topics for future research.

Environmental Implications of Alternative-Fueled Automobiles: Air Quality and Greenhouse Gas Tradeoffs

“…Finally, not all of the regulated exhaust emissions are higher during the off-cycle mode (24). Unfortunately, there are many barriers to determining realworld emissions even for conventional vehicles (14,25,26); therefore, we use a simplified method to calculate exhaust emissions.…”

“…We model two sets of cars, one with conventional automobile range (defined as the product of the Taurus fuel tank capacity and combined city/ highway fuel economy), 595 km, and the other, a set of niche "urban cars", with 160-km range. Although consumers have rejected the EV-1 in part because of its limited range, the majority of household vehicle trips in California are less than 10 km in length, and the average trip time is 10 min (14). We calculate the vehicle lifetime as 225 300 km based on data in ref 15.…”

“…Although the non-methane organic gas emissions from the alternative fuels have a lower reactivity than those from gasoline, we do not include this in our analysis. Since FTP and off-cycle driving cycle PM emissions from properly functioning gasoline, CNG, and M85 vehicles are reported to be low (14) and the ULEV PM standard only applies to diesel vehicles, we consider PM from these vehicles in the toxics section since diesel PM is an EPA-designated air toxic. Since emissions levels of a vehicle are not correlated with fuel economy (23,27), we assume identical emissions factors for the 160-and 575-km range vehicles.…”

A potential remote sensor of CO in vehicle exhausts using 2.3 µm diode lasers

“…Although the 38% reduction of ambient CO concentration between 1988 and 1997 [1] reflected the considerable reduction in emission from automobiles, the improvements are not nearly as large as had been expected and some serious defects have been identified in current vehicle inspection and maintenance (I/M) programmes [2]. Because approximately 50% of the CO is emitted by 10% of the vehicle fleet, on-road remote sensing devices (RSD) are considered an especially attractive I/M tool to supplement current I/M programmes and to focus resources on gross polluters [2][3][4][5]. In addition, RSD can improve vehicle emission inventories [3,4], which air pollution control agencies use to identify the most costeffective control measures, to determine the effectiveness of control programmes and to predict future air quality through use of simulation models.…”

“…Because approximately 50% of the CO is emitted by 10% of the vehicle fleet, on-road remote sensing devices (RSD) are considered an especially attractive I/M tool to supplement current I/M programmes and to focus resources on gross polluters [2][3][4][5]. In addition, RSD can improve vehicle emission inventories [3,4], which air pollution control agencies use to identify the most costeffective control measures, to determine the effectiveness of control programmes and to predict future air quality through use of simulation models. Data from RSD can also be used to assess the real rather than computer-modelled effectiveness Corresponding author.…”