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Atmospheric Environment (v.39, #13)
12th International Symposium, Transport and Air Pollution, Avignon, France, 16–18 June 2003
by Robert Joumard (pp. 2339-2340).
Effect of vehicle characteristics on unpaved road dust emissions by J.A. Gillies; V. Etyemezian; H. Kuhns; D. Nikolic; D.A. Gillette (pp. 2341-2347).
This paper presents PM10 fugitive dust emission factors for a range of vehicles types and examines the influence of vehicle and wake characteristics on the strength of emissions from an unpaved road. Vertical profile measurements of mass concentration of the passing plumes were carried out using a series of 3 instrumented towers. PM10 emission fluxes at each tower were calculated from knowledge of the vertical mass concentration profile, the ambient wind speed and direction, and the time the plume took to pass the towers. The emission factors showed a strong linear dependence on speed and vehicle weight. Emission factors (EF=grams of PM10 emitted per vehicle kilometer traveled) ranged from approximately EF=0.8×(kmh−1) for a light (∼1200kg) passenger car to EF=48×(kmh−1) for large military vehicles (∼18000kg). In comparison to emission estimates derived using US EPA AP-42 methods the measured emission factors indicate larger than estimated contributions for speeds generally>10–20kmh−1 and for vehicle weights>3000kg. The size of a wake created by a vehicle was observed to be dependent on the size of the vehicle, increasing roughly linearly with vehicle height. Injection height of the dust plume is least important to long-range transport of PM10 under unstable conditions and most important under stable atmospheric conditions.
Keywords: Keyword; Fugitive dust; PM; 10; Unpaved road dust emissions; Emission factors
Diesel vs. gasoline emissions: Does PM from diesel or gasoline vehicles dominate in the US? by Alan W. Gertler (pp. 2349-2355).
In the US, the majority of the on-road fleet and vehicle miles travelled are attributed to light-duty vehicles, which are fuelled almost entirely by gasoline. However, due to their significantly higher PM emission rates, emissions inventories have tended to attribute the majority of the mobile source PM to contributions from heavy-duty diesel vehicles and strategies to reduce mobile source PM have focused on the contribution from this source. A limited number of source attribution studies have implied that PM emission inventories over-estimate the diesel contribution and emissions from gasoline vehicles may be greater than previously believed. Other receptor-modelling studies have found diesel vehicles to be the dominant source of motor vehicle PM. The former conclusion is supported by recent on-road PM emission rate results obtained in a highway tunnel and a series of crossroad experiments. This paper describes the often-conflicting results obtained from receptor modelling studies and emission inventories and uses on-road emission factor results to estimate the relative contributions from the diesel and gasoline sectors of the fleet.
Keywords: Emissions inventory; Receptor models; Emission factors; Particulate matter
Transport and Environment Database System (TRENDS): Maritime air pollutant emission modelling by Aliki Georgakaki; Robert A. Coffey; Graham Lock; Spencer C. Sorenson (pp. 2357-2365).
This paper reports the development of the maritime module within the framework of the Transport and Environment Database System (TRENDS) project. A detailed database has been constructed for the calculation of energy consumption and air pollutant emissions. Based on an in-house database of commercial vessels kept at the Technical University of Denmark, relationships between the fuel consumption and size of different vessels have been developed, taking into account the fleet's age and service speed. The technical assumptions and factors incorporated in the database are presented, including changes from findings reported in Methodologies for Estimating air pollutant Emissions from Transport (MEET). The database operates on statistical data provided by Eurostat, which describe vessel and freight movements from and towards EU 15 major ports. Data are at port to Maritime Coastal Area (MCA) level, so a bottom-up approach is used. A port to MCA distance database has also been constructed for the purpose of the study. This was the first attempt to use Eurostat maritime statistics for emission modelling; and the problems encountered, since the statistical data collection was not undertaken with a view to this purpose, are mentioned. Examples of the results obtained by the database are presented. These include detailed air pollutant emission calculations for bulk carriers entering the port of Helsinki, as an example of the database operation, and aggregate results for different types of movements for France. Overall estimates of SO x and NO x emission caused by shipping traffic between the EU 15 countries are in the area of 1 and 1.5 million tonnes, respectively.
Keywords: Maritime transport; Air pollutant emissions
A methodology for modelling and measuring traffic and emission performance of speed control traffic signals by Margarida C. Coelho; Tiago L. Farias; Nagui M. Rouphail (pp. 2367-2376).
In an attempt to control speeds and reduce crashes, traffic signals are being installed at several locations on highways to serve as speed reduction devices. One concern about this type of signals is that while they may be effective in reducing high speed crashes, they not only stop traffic that is exceeding the speed limit, but other traffic on the approach that is not. As a result, vehicle emissions are likely to increase, because of the existence of excessive delays, queue formation and speed change cycles for approaching traffic. An approach, based on experimental measurements and on modelling traffic and emission performance of speed control traffic signals, is presented here in order to explain the interaction between the signal control variables (for example minimum signal settings, speed threshold setting and minimum green call scenarios) and environmental and traffic performance variables, in particular, carbon monoxide, nitric oxide and hydrocarbons emissions and delay. The experimental data for validation were gathered on Highway N6, connecting the cities of Lisbon and Cascais, in Portugal. The main conclusions of the present research are that, for traffic flow values corresponding to 50% of the road capacity estimate for a traffic signal approach, 85% of the speed violators are effectively stopped, while the fraction of vehicles unfairly stopped reaches 30%. Concerning emissions the presence of signals leads to an increase in CO emissions of about 15%, while NO and HC emissions increase by 10% and 40%, respectively. It was also concluded that the control of speed violators increases with traffic flow. As a trade-off, overall traffic delay will also increase as well as the number of vehicles that are unfairly stopped.
Keywords: Modal emissions approach; Numerical model; Field measurements; Speed violator; Traffic delay; Traffic calming; Safety
A study of trace metal concentration of urban airborne particulate matter and its role in free radical activity as measured by plasmid strand break assay by J.J.N. Lingard; A.S. Tomlin; A.G. Clarke; K. Healey; A.W.M. Hay; C.P. Wild; M.N. Routledge (pp. 2377-2384).
Epidemiological studies report a correlation between PM10 concentration and exacerbation of health effects. No clear evidence exists as to whether chemical toxicity, particle-size, or a combination of the two is responsible. This study aims to assess the influence of these factors on DNA strand breakage utilising size-fractionated roadside particulate samples. Samples were collected at two busy roadside and one urban background site. The concentrations of: Cr, Cu, Fe, Mn, Ni and Zn, were analysed by atomic absorption spectrometry. Based on average concentrations, Fe was found to be the most abundant element, predominantly concentrated in the coarser size range of 4.7–5.8μm. The other elements, present at much lower concentrations, were dominant in the smaller size fractions. Aqueous extracts of these size-segregated samples were used to measure the genotoxic effect of PM10 on DNA by plasmid strand break assay, showing that strand breaks were induced. PM10 in the smaller size fractions induced the highest levels of damage.
Keywords: PM; 10; Urban particulates; Size-fractionated; Trace metals; DNA; Plasmid strand break
Chemical characterization of emissions from advanced technology light-duty vehicles by Lisa Graham (pp. 2385-2398).
Results of detailed emissions measurements of seven 2000 model year advanced technology vehicles are reported. Six of the seven vehicles were imported from Europe and Japan and are not yet available for sale in Canada. Three of the vehicles were with direct injection diesel (DDI) technology, three with gasoline direct injection (GDI) technology and one vehicle was a gasoline–electric hybrid. It is expected that vehicles with these technologies will be forming a larger fraction of the Canadian light-duty vehicle fleet in the coming years in response to requirements to reduce greenhouse gas emissions from the transportation sector in support of Canada's ratification of the Kyoto Protocol; and as a result of improving fuel quality (most notably reducing the sulphur content of both diesel and gasoline). It is therefore important to understand the potential impacts on air quality of such changes in the composition of the vehicle fleet. The emissions from these vehicles were characterized over four test cycles representing different driving conditions. Samples of the exhaust were collected for determining methane, non-methane hydrocarbons and carbonyl compounds for the purposes of comparing ozone-forming potential of the emissions. Although these vehicles were not certified to Canadian emissions standards as tested, all vehicles met the then current Tier 1 emission standards, except for one diesel vehicle which did not meet the particulate matter (PM) standard. The DDI vehicles had the highest NO X emissions, the highest specific reactivity and the highest ozone-forming potential of the vehicles tested. When compared to conventional gasoline vehicles, the ozone-forming potential was equivalent. The GDI vehicles had lower NO X emissions, lower specific reactivity and lower ozone-forming potential than the conventional gasoline vehicles. Both the diesel and GDI vehicles had higher PM emissions than the conventional gasoline vehicles. The gasoline–electric hybrid vehicle had the lowest emissions, lowest specific reactivity, lowest ozone-forming potential and highest fuel economy of all vehicles tested.
Keywords: Emissions characterization; Diesel direct injection; Gasoline direct injection; Gasoline–electric hybrid; Non-methane hydrocarbons; Carbonyl compounds; Ground-level ozone-forming potential
Establishing an air pollution monitoring network for intra-urban population exposure assessment: A location-allocation approach by Pavlos S. Kanaroglou; Michael Jerrett; Jason Morrison; Bernardo Beckerman; M. Altaf Arain; Nicolas L. Gilbert; Jeffrey R. Brook (pp. 2399-2409).
This study addresses two objectives: (1) to develop a formal method of optimally locating a dense network of air pollution monitoring stations; and (2) to derive an exposure assessment model based on these monitoring data and related land use, population, and biophysical information. Previous studies have located monitors in an ad hoc fashion, favouring the placement of monitors in traffic “hot spots� or in areas deemed subjectively to be of interest. We apply our methodology in locating 100 nitrogen dioxide monitors in Toronto, Canada. Locations identified by the method represent land use, transportation infrastructure and the distribution of at-risk populations. Our exposure assessments derived from the monitoring program produce reasonable estimates at the intra-urban scale. The method for optimally locating monitors may have widespread applicability for the design of pollution monitoring networks, particularly for measuring traffic pollutants with fine-scale spatial variability.
Keywords: Air pollution; Traffic emissions; Monitoring networks; Location-allocation models; Health effects assessment
Operating conditions of buses in use in the Ile-de-France region of France for the evaluation of pollutant emissions by Andre Michel André; B. Bénédicte Garrot; Yves Roynard; Robert Vidon; Patrick Tassel; Pascal Perret (pp. 2411-2420).
This study is intended to link the pollutant emissions from buses to their driving conditions and to the urban context. Envisaged in the case of the Ile-de-France region of France, this procedure constitutes a methodological basis for characterising bus networks by using geographic and bus operation databases.Firstly, the bus routes are characterised by linking analyses of bus operating conditions and urban characteristics collected and managed by a Geographic Information System. This multidimensional analysis provides bus-route profiles according to the types of areas served.Secondly, one vehicle of a bus route from each of the categories thus defined was instrumented in order to measure its operating parameters during commercial use. The parameters measured include engine operation, the speed and location of the vehicle, passenger load, load linked to the road profile, and electrical and pneumatic loads.After outlining the methodological approach to network characterisation, a description is given of the instrumental protocol followed by the general results of the experiments. In all, over 25,000km were recorded over 1600h of driving, for which the main operating parameters were measured at time intervals of 1s. Preliminary analyses (characterisation of urban areas) and the localisation of the recordings enable linking bus operating conditions with local specificities. The bus operating conditions (speeds, congestion, load, etc.) are analysed as a function of the routes and the geographical and urban specificities of the areas served.This data is then analysed in order to formulate driving cycles representative of real traffic conditions and that serve as the basis for measuring the real pollutant emissions of buses on a vehicle test bench. These driving cycles will then enable associating pollutant emissions with the corresponding driving conditions and geographical areas.
Keywords: Vehicle; Traffic; Instrumentation; Speed; Driving cycle
Fine particulate (PM2.5–PM1) at urban sites with different traffic exposure by Michele Giugliano; Giovanni Lonati; Paola Butelli; Laura Romele; Ruggero Tardivo; Mario Grosso (pp. 2421-2431).
Fine particulate concentration data resulting from several monitoring campaigns performed in the city of Milan at urban sites with different exposure to the emission sources are presented. Low volume PM2.5 and PM1 samplers are utilised together with a low volume optical analyser, enabling the intercomparison between the measurements obtained by the gravimetrical and the optical method. The concentration levels observed at the different sites are compared in order to point out intra-site seasonal differences and inter-site differences for corresponding seasons of the year. These different concentration levels are analysed and explained considering the exposure to the primary emissions and accounting for the role of meteorology. PM10, PM2.5 and PM1 are described in terms of the distribution of 1-h concentration data and their relative mass fractions are determined. In order to assess the significance of secondary sources of fine particulate, a PM2.5 high volume sampler is utilised for the collection of dust-loaded filters to be analysed for chemical characterisation. The composition of PM2.5 emission from traffic is investigated by analysing 24-h samples from an urban tunnel site (TU): data on carbonaceous species, organic carbon (OC) and elemental carbon (EC), are obtained and the ratio between these species is evaluated for real traffic emissions. Secondary organic aerosol (SOA) contribution to PM2.5 mass in ambient air is assessed by means of the primary OC/EC ratio approach, based on chemical data of the filters from the TU. Organic and inorganic secondary production in the outdoor atmosphere is contributing for about 75% of PM2.5 mass in winter and 40% in summer: as a consequence, effective long-term actions, still controlling the emissions of primary pollutants too, are required for air quality standards attainment and the potentiality of short-term interventions, as traffic restriction, appears quite limited.
Keywords: Gravimetric measurements; Optical measurements; Chemical characterisation; Urban area; Real traffic; OC/EC method; Secondary organic aerosol
Regulated and nonregulated diesel and gasoline cold start emissions at different temperatures by Martin Weilenmann; Patrik Soltic; Christian Saxer; A.-M. Anna-Maria Forss; Norbert Heeb (pp. 2433-2441).
The emissions of modern cars are usually reduced in warm engine conditions by catalysts. Consequently emissions are significantly higher during the cold start, i.e. the warm-up phase of the car. The duration of this period and the emissions produced during it depend on the ambient temperature as well as on the initial temperature of the car's systems.The cold start emissions of Euro-3 gasoline cars, Euro-2 diesel cars and old pre-Euro-1 gasoline cars were investigated at cold ambient temperatures. Since the goal was to get real-world emissions, the measurements were done with cars belonging to private owners taken straight from the road with no maintenance. The chassis dynamometer tests were carried out at +23, −7 and −20°C. The test cycle employed is a representative urban ride from a real-world driving behaviour study. Besides the regulated pollutants, methane, benzene and toluene were also measured online by chemical ionisation mass spectrometry.
Keywords: Cold ambient emissions; Online emission measurement; Real-world emissions; Passenger cars; Emission factor
Towards accurate instantaneous emission models by Delia Ajtay; Martin Weilenmann; Patrik Soltic (pp. 2443-2449).
To address the needs of researchers and policy makers on local levels, a microscopic (i.e. at vehicle level) instantaneous emission model is being developed. This model aims to predict vehicle fuel consumption and emissions for a given speed profile, for various vehicle loads, slopes and gear shift scenarios.Instantaneous emission modelling maps the emissions at a given time to their generating “engine state�. To improve the existing models, an analysis of some preconditions must be made: owing to the frequency content of the engine and emission signals, they should be measured on a 10Hz basis or faster.Additionally, the emission signals measured in a test are delayed dynamically, owing to the transport from the engine to the analysers. This transport must be compensated for by time-varying approaches. The modelling and compensation for the gas transport in dilution systems is presented here.With these preconditions fulfilled, new instantaneous emission models are developed and their improvement in quality is checked by comparing them with older models. Further improvements to describe the transient emissions of vehicles are sketched.
Keywords: Vehicle; Pollutant; Emission factors; Dynamic compensation; Dynamic emission mapping
Real life evaluation of the emission reduction potential of a city bus retrofitted with a continuous regenerating trap by Martine Van Poppel; Guido Lenaers (pp. 2451-2457).
A cost effective measure to reduce particulate matter (PM) emissions of city buses is retrofitting with a continuous regenerating trap (CRT). In this paper, the performance of the CRT is evaluated in real life conditions using an on-the-road emission and energy measurement system developed previously in our laboratory.The CRT is found to reduce PM emissions to over 90% thereby also reducing CO and THC to at least 65%. No significant NO x change is detected. The raise in fuel consumption is not significant. The exhaust gas temperature at the CRT is over 250°C for 70% of the time thus easily fulfilling the manufacturer's demand. The demand for a NO x/PM ratio of 15 is at least realised during 70% of the time.Follow-up measurements after 1 year showed no deterioration of the CRT.
Keywords: Particulate trap; Particulate matter; Emissions; On-board; Diesel
Pollution dispersion at an urban motorway tunnel portal: Comparison of the small-scale predictive study with the actual conditions measured on the site by Bruno Brousse; Bruno Vidal; Xavier Ponticq; Ghislaine Goupil; R. René Alary (pp. 2459-2473).
This paper presents a study on the environmental impact of vehicle exhausts at the south portal of the Landy tunnel located north of Paris, France. This study is based on a 1995 dispersion study using a hydraulic model and a 2002 campaign of in situ measurements.The 1995 study, conducted before the motorway covering was built, was aimed at comparing the theoretical NO2 concentrations, obtained with a hydraulic scale model, with the permissible thresholds imposed by French regulations. The NO2 concentrations obtained with the scale model were found to be reasonable, but as a precaution it was decided to retain a contingency option to subsequently install a massive extraction chimney to reduce exhaust emission levels at the portal.The 2002 in situ measurement campaign was aimed at measuring the actual pollution levels in the vicinity of the Landy tunnel south portal. The statistical analysis showed that the NO2 concentrations were higher on the east side of the road than the west, but still 5 to 10 times lower than at the exhaust, and are of the same order of magnitude as alongside other major Paris motorways. The PM10 measurements were in line with regulatory reference values on both sides of the road.Comparing the 1995 study and the 2002 in situ measurements showed a certain consistency but also highlighted the complexity of the phenomena involved and the difficulty of identifying the influence of the tunnel exhaust on the NO2 levels at the roadside.
Keywords: Hydraulic model; In situ measurements; Nitrogen oxides; PM; 10; Regulation
Local impact of air pollution: lessons from recent practices in economics and in public policies in the transport sector by J.-P. Jean-Pierre Nicolas; Fabien Duprez; Sandrine Durand; Fabrice Poisson; P.-L. Pierre-Louis Aubert; Mireille Chiron; Yves Crozet; Jacques Lambert (pp. 2475-2482).
This paper focuses on the economic valuation of the impact of local air pollution. Two main issues are considered: 1. The scientific issue: what is estimated, how and why? The main studies from the nineties are presented here. Two strong issues are stressed, with the diversity of valuation methods, on the one hand, and the debates on how to take the long term into account and the discount technique, on the other. 2. The political issue: how the results from the economic field are analysed and used to establish official values for public policies? The methods used in the transport sector in three different European countries (France, Sweden and Switzerland) are studied here.To conclude, we highlight the discrepancy between these two processes and, wherever possible, offer solutions to reach better synergy.
Keywords: Local air pollution; External costs; Economic valuation; Official values; Public decision; International comparison
Particulate matter regulation for two-stroke two wheelers: Necessity or haphazard legislation? by Rudolf Rijkeboer; Dion Bremmers; Zissis Samaras; Leonidas Ntziachristos (pp. 2483-2490).
Although interest in particulate emissions has increased considerably during recent years, the subject of particulate matter (PM) emissions from small two-stroke engines used in road vehicles is still largely unexplored. This paper presents the results of an investigation, which examined the typical emission level and the typical characteristics of two-stroke PM, as well as the possible impact on the (urban) environment, all in comparison to diesel engines. Attention was also paid to the possible problems concerning the measurement of two-stroke PM and the possibilities to add a PM requirement to the moped type approval procedure. It is demonstrated that despite the significant PM emission levels of current two wheelers, particle characteristics are different compared to diesel exhaust PM and hence following a diesel-like procedure to quantify particle emissions may not be the indicated approach. Hence, based on the experimental evidence and the foreseen technology developments, recommended steps forward are proposed, taking into account the need for efficient regulation of PM and the particularities of the specific vehicle technology.
Keywords: Particulate matter emission; Two-stroke; Moped; Motorcycle; Legislation
The stakes of air pollution in the transport sector, from the French case by Robert Joumard (pp. 2491-2497).
The main pollutants are listed for today and the future according to the progression of air quality, as measured in France and in the European Union during the 1990s, the progression of pollutant emissions of road transport in France, as calculated for the period 1970–2020, and the progression of public concern regarding air pollution and environment. These pollutants are headed by carbon dioxide, followed by nitrogen oxides and fine particulates. The stakes in terms of technology and transport supply and demand are assessed. These stakes for society allow us to propose several directions of research in the field of air pollution that respond more to current problems than to those of the past (greenhouse effect, sensitive pollution, photochemical pollution, life cycle approach, aggregated indicators).
Keywords: Transport emissions; Air quality; Abatement technology; Research policy
Statistical analysis of the vehicle pollutant emissions derived from several European road tunnel studies by Christina A. Colberg; Bruno Tona; Giovanni Catone; Christian Sangiorgio; Werner A. Stahel; Peter Sturm; Johannes Staehelin (pp. 2499-2511).
Real-world emission rates of road traffic can be quantified by measurements in road tunnels. Emission factors (EFs) of in-use vehicles can be determined and the impact of major changes in technology and fuel composition can be estimated. Here, we present tunnel measurements of nitrogen oxides (NO x), carbon monoxide (CO), and total volatile organic compounds (t-VOCs) performed in spring 2001 in the Lundby tunnel (Sweden), in fall 2001 in the Plabutsch tunnel (Austria) and in fall 2002 in the Gubrist tunnel (Switzerland). In this paper, we derive EFs for light and heavy duty vehicles (LDVs and HDVs) by the statistical method of linear and non-linear regression analysis. The results demonstrate the large effect of the tunnel road gradient for NO x emissions of HDVs, whereas the influence of the road gradient is less pronounced for LDV emissions of NO x and CO. The developed statistical modeling approach allows the determination of EFs as a function of vehicle speed. The results also indicate a dependence of the EFs on the day of the week, probably caused by differences in the fleet composition.
Keywords: Statistical modeling; Road traffic emissions; Emission factors; Tunnel measurements; Real-world emissions