Determining Gaseous Emission Factors and Driver’s Particle Exposures during Traffic Congestion by Vehicle-Following Measurement Techniques

Abstract

Vehicle gaseous emissions (NO, CO, CO 2 , and hydrocarbon [HC]) and driver's particle exposures (particulate matter Ͻ1 m [PM 1 ], Ͻ2.5 m [PM 2.5 ], and Ͻ10 m [PM 10 ]) were measured using a mobile laboratory to follow a wide variety of vehicles during very heavy traffic congestion in Macao, Special Administrative Region, People's Republic of China, an urban area having one of the highest population densities in the world. The measurements were taken with high time resolution so that fluctuations in the emissions can be seen readily during vehicle acceleration, cruising, deceleration, and idling. The tests were conducted in close proximity to the vehicles, with the inlet of a five-gas analyzer mounted on the front bumper of the mobile laboratory, and the distance between the vehicles was usually within several meters. To measure the driver's particle exposures, the inlets of the particle analyzers were mounted at the height of the driver's breathing position in the mobile laboratory, with the driver's window open. A total of 178 and 113 vehicles were followed individually to determine the gaseous emission factor and the driver's particle exposures, respectively, for motorcycle, passenger car, taxi, truck, and bus. The gaseous emission factors were used to model the roadside air quality, and good correlations between the modeled and monitored CO, NO 2 , and nitrogen oxide (NO x ) verified the reliability of the experiments. Compared with petrol passenger cars and petrol trucks, diesel taxies and diesel trucks emitted less CO but more NO x . The impact of urban canyons is shown to cause a significant increase in the PM 1 peak. The background concentrations contributed a significant amount of the driver's particle exposures.

Application of positive matrix factorization to on-road measurements for source apportionment of diesel- and gasoline-powered vehicle emissions in Mexico City

“…In the US, emission factors of vehicles that are 10-12 years old are ∼4 times higher than those of vehicles five years old or younger (Bishop and Stedman, 2008). Chases of vehicles by a mobile laboratory in Macao in 2004 found CO emission factors of 230 g kg −1 for passenger cars at least 10 years old and 32 g kg −1 for newer cars, a factor of seven difference (Tang and Wang, 2006). The MCMA's policy Hoy No Circula, which restricts vehicles from driving on certain days according to their license plate numbers, may have slowed the improvement in emissions from passenger cars because some households acquire additional vehicles for use on alternating days, and these tend to be older (Davis, 2008) and therefore more polluting.…”

Risk assessment of traffic-related air pollution in a world heritage city

“…Based on the measurement, the emission factors for five categories of vehicles, i.e., motorcycle, passenger car, taxi, truck, and bus, had been calculated. The details of the vehicle following measurement and the calculation of the emission factors have been reported by Tang and Wang (2006).…”

Real-world emissions of gasoline passenger cars in Macao and their correlation with driving conditions

“…On-road emission measurements have become very important as they can provide real-world emission status of in-use vehicles. There are several on-road emission measurement methods including chasing car measurement (Tang and Wang 2006;Westerdahl et al 2009), remote sensing and on-board measurement. With the recent development of portable emissions measurement system (PEMS), researchers around the world have measured the on-board emission characteristics of motor vehicles under real-world driving conditions.…”