Vehicle, Driver and Atmospheric Factors in Light-Duty Vehicle Particle Number Emissions (original) (raw)
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Vehicle Driver & Atmospheric Factors in Light-Duty Vehicle Particle Number Emissions
2014
Made possible by the collection of on-board tailpipe emissions data, this research identifies road and driver factors that are associated with a relatively understudied tailpipe pollutant from lightduty vehicles: ultrafine particle number emissions. High emission events (HEE) of ultrafine particle number (PN) emissions occurred most frequently at locations with steep upgrades or locations that required moderate to rapid accelerations (\u3e3 mph/s). The analysis revealed that less than 2% of the time driving was responsible for almost a third of all ultrafine particles emitted along the designated 17-mile test route for a sample of 22 drivers. Variables identified in a generalized linear model as significant to PN emissions include measures of engine speed (RPM), driver behavior (speed and acceleration rates), and road geometry (grade). These factors account for approximately 61% of the variability measured. Few modal emissions models estimate PN emissions; however, this research has...
Quantification of Particle Number Emission Factors for Motor Vehicles from On-Road Measurements
Environmental Science & Technology, 2005
The database on particle number emission factors has been very limited to date despite the increasing interest in the effects of human exposure to particles in the submicrometer range. There are also major questions on the comparability of emission factors derived through dynamometer versus on-road studies. Thus, the aims of this study were (1) to quantify vehicle number emission factors in the submicrometer (and also supermicrometer) range for stop-start and free-flowing traffic at about 100 km h(-1) driving conditions through extensive road measurements and (2) to compare the emission factors from the road measurements with those obtained previously from dynamometer studies conducted in Brisbane. For submicrometer particles the average emission factors for Tora Street were estimated at (1.89 +/- 3.40) x 10(13) particles km(-1) (mean +/- standard error; n = 386) for petrol and (7.17 +/- 2.80) x 10(14) particles km(-1) (diesel; n = 196) and for supermicrometer particles at 2.59 x 10(9) particles km(-1) and 1.53 x 10(12) particles km(-1), respectively. The average number emission factors for submicrometer particles estimated for Ipswich Road (stop-start traffic mode) were (2.18 +/- 0.57) x 10(13) particles km(-1) (petrol) and (2.04 +/- 0.24) x 10(14) particles km(-1) (diesel). One implication of the conclusion that emission factors of heavy duty diesel vehicles are over 1 order of magnitude higher than emission factors of petrol-fueled passenger cars is that future control and management strategies should in particular target heavy duty vehicles, as even a moderate decrease in emissions of these vehicles would have a significant impact on lowering atmospheric concentrations of particles. The finding that particle number emissions per vehicle-km are significantly larger for higher speed vehicle operation has an important implication on urban traffic planning and optimization of vehicle speed to lower their impact on airborne pollution. Additionally, statistical analysis showed that neither the measuring method (dynamometer or on-road), nor data origin (Brisbane or elsewhere in the world), is associated with a statistically significant difference between the average values of emission factors for diesel, petrol, and vehicle fleet mix. However, statistical analyses of the effect of fuel showed that the mean values of emission factors for petrol and diesel are different at a 5% significance level.
Particle Emissions Characteristics of Different On-Road Vehicles
SAE Technical Paper Series, 2003
Due to the stringent emission standards set worldwide, particulate matter (PM) emissions from diesel vehicles have been significantly curtailed in the last decade, and are expected to be reduced even further in the future. This evolution has brought forward two main issues: whether PM emissions should only be regulated for diesel vehicles and whether gasoline powered vehicles can be further neglected from PM emission inventories. This paper addresses these issues comparing the characteristics of particle emissions from a current diesel passenger car, a gasoline one and two small two-wheelers. It is shown that the gasoline car is a negligible source of particle emissions while the two-wheelers may be even more significant particle sources than the diesel car.
Revisiting Total Particle Number Measurements for Vehicle Exhaust Regulations
Atmosphere
Road transport significantly contributes to air pollution in cities. Emission regulations have led to significantly reduced emissions in modern vehicles. Particle emissions are controlled by a particulate matter (PM) mass and a solid particle number (SPN) limit. There are concerns that the SPN limit does not effectively control all relevant particulate species and there are instances of semi-volatile particle emissions that are order of magnitudes higher than the SPN emission levels. This overview discusses whether a new metric (total particles, i.e., solids and volatiles) should be introduced for the effective regulation of vehicle emissions. Initially, it summarizes recent findings on the contribution of road transport to particle number concentration levels in cities. Then, both solid and total particle emission levels from modern vehicles are presented and the adverse health effects of solid and volatile particles are briefly discussed. Finally, the open issues regarding an appr...
Environmental Science and Pollution Research, 2009
Background, aim, and scope Urban motor vehicle fleets are a major source of particulate matter pollution, especially of ultrafine particles (diameters < 0.1 µm), and exposure to particulate matter has known serious health effects. A considerable body of literature is available on vehicle particle emission factors derived using a wide range of different measurement methods for different particle sizes, conducted in different parts of the world. Therefore the choice as to which are the most suitable particle emission factors to use in transport modelling and health impact assessments presented as a very difficult task. The aim of this study was to derive a comprehensive set of tailpipe particle emission factors for different vehicle and road type combinations, covering the full size range of particles emitted, which are suitable for modelling urban fleet emissions. Materials and methods A large body of data available in the international literature on particle emission factors for motor vehicles derived from measurement studies was compiled and subjected to advanced statistical analysis, to determine the most suitable emission factors to use in modelling urban fleet emissions. Results This analysis resulted in the development of five statistical models which explained 86%, 93%, 87%, 65% and 47% of the variation in published emission factors for particle number, particle volume, PM 1 , PM 2.5 and PM 10 respectively. A sixth model for total particle mass was proposed but no significant explanatory variables were identified in the analysis. From the outputs of these statistical models, the most suitable particle emission factors were selected. This selection was based on examination of the statistical robustness of the statistical model outputs, including consideration of conservative average particle emission factors with the lowest standard errors, narrowest 95% confidence intervals and largest sample sizes, and the explanatory model variables, which were Vehicle Type (all particle metrics), Instrumentation (particle number and PM 2.5), Road Type (PM 10) and Size Range Measured and Speed Limit on the Road (particle volume). Discussion A multiplicity of factors need to be considered in determining emission factors that are suitable for modelling motor vehicle emissions, and this study derived a set of average emission factors suitable for quantifying motor vehicle tailpipe particle emissions in developed countries. Conclusions The comprehensive set of tailpipe particle emission factors presented in this study for different vehicle and road type combinations enable the full size range of particles generated by fleets to be quantified, including ultrafine particles (measured in terms of particle number). These emission factors have particular application for regions which may have a lack of funding to undertake measurements, or insufficient measurement data upon which to derive emission factors for their region. Recommendations and perspectives In urban areas motor vehicles continue to be a major source of particulate matter pollution and of ultrafine particles. It is critical that in order to manage this major pollution source methods are available to quantify the full size range of particles emitted for traffic modelling and health impact assessments.
Atmospheric Environment, 2006
In-use, fuel-based motor vehicle emission factors were determined using measurements made in a highway tunnel in Pittsburgh, Pennsylvania. Concentrations of PM 2.5 mass, CO, CO 2 , and NO x were measured continuously. Filter-based measurements included PM 2.5 mass, organic and elemental carbon (OC and EC), inorganic ions and metals. Fuel-based emission factors for each pollutant were calculated using a fuel-carbon balance. The weekday traffic volume and fleet composition varied in a consistent diurnal pattern with the estimated fraction of fuel consumed by heavy-duty diesel vehicle (HDDV) traffic ranging from 11% to 36%. The emission rate of most species showed a significant dependence on sample period. NO x , PM 2.5 , EC and OC emission factors were significantly larger during the early morning, truckdominated period. Emissions of particulate metals associated with brake wear (Cu, Sb, Ba and potentially Ga) were emitted at higher rates during the rush-hour period, which is characterized by slower, stop-and-go traffic. Emission rates of crustal elements (Fe, Ca, Mg, Li), Zn and Mn were highest during the early-morning period when there was more heavytruck traffic. A seasonal shift in average OC/EC ratio for the rush-hour period was observed; fall and summer OC/EC ratios are 1.070.6 and 0.2670.06, respectively. Potential causes for this shift are increased partitioning of semi-volatile organic compounds into the gas phase during the summer months and/or effects of seasonal changes in fuel formulation. Emission factors for HDDV and light-duty vehicles (LDV) classes were estimated using a linear regression of emission factor as a function of fleet composition. The extrapolated emission factors generally agree with previously published measurements, though a substantial range in published values is noted. r
Particle Mass Emission Rates from Current-Technology, Light-Duty Gasoline Vehicles
Journal of the Air & Waste Management Association, 2000
Now that the U.S. Environmental Protection Agency has promulgated new National Ambient Air Quality Standards for PM 2.5 , work will begin on generating the data required to determine the sources of ambient PM 2.5 and the magnitude of their contributions to air pollution. This paper summarizes the results of an Environmental Research Consortium program, carried out under the auspices of the U.S. Council for Automotive Research. The program focused on particulate matter (PM) emissions from representative, current-technology, light-duty gasoline vehicles produced by DaimlerChrysler Corp., Ford Motor Co., and General Motors Corp. The vehicles, for the most part taken from the manufacturer's certification and durability fleets, were dynamometer-tested using the three-phase Federal Test Procedure in the companies' laboratories. The test fleet was made up of a mixture of both lowmileage (2K-35K miles) and high-mileage (60K-150K miles) cars, vans, sport utility vehicles, and light trucks. For each vehicle tested, PM emissions were accumulated over 4 coldstart tests, which were run on successive days. PM emission rates from the entire fleet (22 vehicles total) averaged less than 2 mg/mile. All 18 vehicles tested using California Phase 2 reformulated gasoline had PM emission rates less than 2 mg/ mile at both low and high mileages. IMPLICATIONS Motor vehicles are a source of PM. The significance of vehicles as contributors to urban environmental particle concentrations needs to be evaluated from both environmental and vehicle measurement data. This report provides particle emissions data for current-technology (1994-1998) gasoline vehicles at both low and high mileages. Particle emission rates for both low-and highmileage vehicles, using California reformulated fuel, are about 2 mg/mile.
Tailpipe emissions from passenger cars of different models: What are the main influencing factors?
Environmental Progress & Sustainable Energy, 2012
Urban air pollution is considered to be a critical environmental and public health issue, with the transportation sector being a major contributor. This study focuses on tailpipe pollutant emissions from light-duty vehicles in real driving conditions. Our principle objective was to identify primary factors that affect the emission rates under different driving styles, fuel grade, engine transmission, and checking/maintenance practices. We observed that emission rates were consistently lower with frequent acceleration and deceleration associated with aggressive driving (AD) compared to relaxed driving (RD) style. This indicates that vehicles driven in town (which are typically driven in a relaxed manner) may require more regular maintenance than vehicles driven on motorways (which are typically driven in an aggressive manner). All pollutant emissions were higher in manual transmission vehicles on both urban roads and motorways than in automatic transmission vehicles. The information generated from this research can help establish framework for pollution mitigation efforts, such as inspection and maintenance programs, and in developing traffic pollution management strategies for national use.
Driver and Road Type Effects on Light-Duty Gas and Particulate Emissions
Transportation Research Record, 2006
An instrumented minivan on a 30-mile (48 km) test route was used to measure second-by-second vehicle operating characteristics as well as tailpipe particulate and gas emissions. Our research objectives are: 1) to quantify the variability of gas and particulate emissions between 12 drivers; and 2) to measure the relative emission level on freeways, signalized arterials, rural two-lane arterials and local roads. The results reaffirm that individual drivers significantly affect emissions levels. All emissions concentrations were also systematically related to road type. Furthermore, drivers could be grouped by emissions level, but these groupings differ by pollutant and by road type. More data are needed to elucidate driver-road type interactions and to characterize the regional driver pool for more robust microscale emissions models. The relative importance of driver type compared to other factors known to affect emissions needs to be quantified. Finally, two key issues were identified as affecting the accuracy of instantaneous emissions measurements: instrument response time effects on data alignment and accurately quantifying the full range of on-road exhaust flow rates.