traffic emission

Atmospheric particulate matter (PM) was fractionated in six aerodynamic sizes, > 7.2, 7.2-3, 3-1.5, 1.5-1, 1-0.5 and < 0.5 µm, using a cascade impactor. These fractions were collected at urban and rural sites during warm and cold seasons. Organic tracer compounds, such as levoglucosan, isoprene, pinene oxidation products, polycyclic aromatic hydrocarbons and quinones, were analyzed by gas chromatography coupled with mass spectrometry. These analyses showed that the composition in the smallest size fractions (< 0.5 µm) was more uniform than in the larger sizes (7.2> PM > 0.5 µm). Thus, markers of photochemically synthesized organic compounds or combustion sources, either biomass burning or traffic emissions, were predominantly observed in the fraction < 0.5 µm, whereas the larger particles were composed of mixed sources from combustion processes, vegetation emissions, soil resuspension, road dust, urban lifestyle activities and photochemically synthesized organic compounds. Important seasonal differences were observed at the rural site. In the < 0.5 µm fraction these were related to a strong predominance of biomass burning in the cold period and photochemically transformed biogenic organic compounds in the warm period. In the 7.2 > PM > 0.5 µm fractions the differences involved predominantly soil-sourced compounds in the warm period and mixed combustion sources, photochemical products and vegetation emissions in the cold. Multivariate curve resolution/alternating least squares showed that these organic aerosols essentially originated from six source components. Four of them reflected primary emissions related to either natural products, e.g., vegetation emissions and upwhirled soil dust, or anthropogenic contri-butions, e.g., combustion products and compounds related to urban lifestyle activities like vehicular exhaust and tobacco smoking. Two secondary organic aerosol components were identified. They accumulated in the smallest (< 0.5 µm) or in the larger fractions (> 0.5 µm) and involved strong or mild photochemical transformations of vegetation precursor molecules, respectively. Toxicologically relevant information was also disclosed with the present approach. Thus, the strong predominance of biomass burning residues at the rural site during the cold period involved atmospheric concentrations of polycyclic aromatic hydrocarbons that were 3 times higher than at the urban sites and benzo[a]pyrene concentrations above legal recommendations.

In this work we examine the possibility of using satellite remote sensors for the detection of air traffic emissions produced during the en-route segment of flight in the Upper Troposphere/Lower Stratosphere region (8000-12,000 m). NO 2 has been considered as the tracer of aircraft plumes with highest possibility of being successfully detected from space. An analysis of the technical potential of the current orbital sensors capable of measuring NO 2 in the proximity of the tropopause has been conducted. In order to estimate an upper bound for the NO 2 column related to aircraft emissions, the Canary Islands Corridor has been selected for conducting a simple emission calculation exercise based on real air traffic and operational data, assuming an ideal atmospheric scenario. The results obtained in this approximation have been compared to the actual information retrieved from space sensors. An in-depth inspection of the NO 2 column data for two particular areas (Canary Islands Corridor and North Atlantic Flight Corridor) obtained in recent years by SCIAMACHY and OMI has also been carried out. The general conclusions of this viability study are not optimistic. The estimated maximum NO 2 column value attributable to aircraft emissions at cruise altitudes were lower than the detection limits associated with SCIAMACHY and OMI for NO 2 column measurements. As a result, detecting and quantifying the actual NO 2 levels in aircraft corridors by space remote sensing is a very challenging task.

In this work we examine the possibility of using satellite remote sensors for the detection of air traffic emissions produced during the en-route segment of flight in the Upper Troposphere/Lower Stratosphere region (8000-12,000 m). NO 2 has been considered as the tracer of aircraft plumes with highest possibility of being successfully detected from space. An analysis of the technical potential of the current orbital sensors capable of measuring NO 2 in the proximity of the tropopause has been conducted. In order to estimate an upper bound for the NO 2 column related to aircraft emissions, the Canary Islands Corridor has been selected for conducting a simple emission calculation exercise based on real air traffic and operational data, assuming an ideal atmospheric scenario. The results obtained in this approximation have been compared to the actual information retrieved from space sensors. An in-depth inspection of the NO 2 column data for two particular areas (Canary Islands Corridor and North Atlantic Flight Corridor) obtained in recent years by SCIAMACHY and OMI has also been carried out. The general conclusions of this viability study are not optimistic. The estimated maximum NO 2 column value attributable to aircraft emissions at cruise altitudes were lower than the detection limits associated with SCIAMACHY and OMI for NO 2 column measurements. As a result, detecting and quantifying the actual NO 2 levels in aircraft corridors by space remote sensing is a very challenging task.

Bio-monitoring of air quality in Amman City was investigated by analyzing 36 cypress tree (Cupressus semervirens L.) bark samples from three sites of different anthropogenic activities at the end of summer season 2001. Cypress barks were found to be a good bio-indicator for air pollution in arid regions. Variation in Pb, Zn, Mn, Cr, Ni, Cd, and Cu contents between sites was observed due to different types of activities. Traffic emissions were found to be the main source of heavy metal pollution in the atmosphere of Amman. Lead content was found to be the highest in highly traffic density areas. The industrial part of the city was characterized by high Zn, Mn, Cr, Ni, and Co contents. No significance variations were found in pH values of the bark between the sites. This was attributed to buffering effect of carbonate in the atmosphere originated from soil of the area.

Estimates of the amount of secondary organic aerosol formed in the atmosphere from the degradation of traffic C6-C12 hydrocarbon emissions in the city of Athens are presented. Around 1.26 tn of organic aerosol is estimated to be produced during a six hours air pollution episode from the aromatic hydrocarbons, the other NMHC groups contributing an additional 0.2 tn. The main contributor to the SOA production is m-xylene. It accounts, together with toluene, for around 50% of the produced organic aerosol. The main aerosol products that are expected to form from the Athens NMHC traffic mixture are nitrophenols. Due to predominant wind flow to the S-SE direction in the area, a portion of these aerosols is likely to contribute to the SOA burden of the marine atmosphere over SE Mediterranean. These results are also relevant to ozone abatement strategies involving species-specific NMHC reductions and affecting fine particulate composition and concentrations.

Quasi-continuous measurements of NO V , CO and C }C hydrocarbons made during the MEDCAPHOT-TRACE experiment in a street canyon with heavy tra$c load were used to estimate the CO/NO V and 36 individual NMHC/NO V tra$c emission ratios in the Athens basin. A tra$c emission inventory has been compiled for Athens and aspects of this inventory were tested against measurements. The results indicate that although the main features of the 9:00 to 15:00 variations of the NMHC/NO V and CO/NO V inventory emission ratios are in agreement with observations, during the rest of the day the "ne structure of the variations of these ratios cannot be accurately predicted by the inventory. Comparison of pollutant emission ratios derived from ambient measurements with emission ratios predicted by existing inventories for Athens reveals serious discrepancies. Further, the experimental results and theoretical considerations indicate that the speciation of evaporative emissions changes with increasing ambient temperature in favour of the most volatile HC species, thus changing the speciation of tra$c emissions during the course of the day. This is an aspect that is not taken into account in present urban photochemical modelling inventories.

During spring time 2002 a field experiment was carried out in the Metropolitan Area of Santiago de Chile at three monitoring sites located along a SW-NE transect that represents upwind, downtown and downwind conditions, respectively. Three consecutive days (30 October-01 November 2002) reflecting different photochemical and meteorological conditions were selected. These days included two workdays and one holiday and thus the effect of different primary emissions could be investigated. A variety of trace gas measurements (O 3 , NO x , CO, volatile organic compounds (VOC)) were obtained at these sites. Alkanes represent the largest VOC fraction at all sites, followed by aromatics and alkenes, the smallest fractions are represented by the alkynes or isoprene. Regarding reactivity ranking propene equivalent values show that during morning hours, alkenes are the most reactive compounds, at noon, aromatics are dominant, and in the afternoon isoprene becomes important. Alkanes do not contribute more than 20% to the total air mass reactivity despite being present at the higher concentration levels. Regarding liquefied petroleum gas (LPG) impacts, we find a threefold decrease of concentrations at the eastern side of the city-and no significant trend at Downtown Santiago-which we ascribe to a switch to natural gas in the higher income eastern side of town. The generation of ozone impacts above 50 ppbv is mainly due to anthropogenic traffic-related hydrocarbons. In addition, traffic emissions are contributing most to the formation of secondary organic aerosols (SOA). A model study was carried out, applying a Lagrange trajectory model coupled with photochemical and aerosol modules. The model results are in good agreement with the observations. Additionally, the relative contribution of the respective hydrocarbons to the ozone production in an air parcel along the trajectory was computed. The model also indicates SOA formation by means of oxidation of higher alkanes, alkenes, and aromatics, the latter being the major contributors to those secondary pollutants.

Characterizations of urban and regional sources of particulate matter (PM) were performed in the Milan area (North of Italy) during Föhn and stagnant (non-Föhn) conditions. The measurements were performed at two different places: in an urban area North of Milan (Bresso) and in a regional area at the EMEP-GAW station in Ispra (about 65 km NW from Milan) during the winter periods of the years 2002-2007. Particle size distributions and chemical bulk analysis of aerosols are combined with single particle mass spectrometry to obtain information about the chemical content of the particles and their mixing state. Föhn conditions are characterized by extremely clean background air from which background aerosol is scavenged, and consequently local sources (here defined as sources between the sampling sites and the mountain range top about 100-150 km away depending on the wind direction) determine the aerosol properties. It was observed that during Föhn events the accumulation mode in the size range 50 nm b d b 300 nm practically disappears and that the size fraction below 50 nm dominates the total number distribution. The significant change in the number size distribution and the large decrease in PM10 mass during Föhn events are accompanied by a significant change in the chemical composition of the particles. Results from bulk chemical analysis showed high amounts of carbonaceous compounds and very low concentrations of ammonium nitrate (as indicator for secondary chemistry) during Föhn episodes, in contrast to stagnant conditions, when secondary components are dominating the aerosol composition. Single particle measurements confirm the high contribution of carbonaceous compounds in locally emitted particles. It was concluded that particles that originated in the urban area come mainly from combustion processes, especially direct traffic emissions, domestic heating and industrial activities, whereas the regionally emitted particles are different with much less traffic contribution. We estimate that under prevailing (non-Föhn) winter conditions, about 50-65% of the aerosol mass load in the city of Milan are caused by local emissions, and about 35-50% come from regional background. This finding suggests that in order to improve air quality in a big city like Milan, it is important to combine local traffic restriction interventions with other long-term regional scale air-quality-measures.

The present study covers an investigation of the trends in air pollution levels of benzene in Danish cities and their relationship with the benzene content in petrol. Petrol samples from the two refineries in Denmark as well as sold petrol from some representative Danish petrol stations were analysed. The benzene content in Danish petrol was reduced from 3.5% for 95 octane prior to 1995 to approx. 2% in 1995 and further to 1% in 1998. Air quality measurements of aromatic VOC are available from two Danish cities; Copenhagen since 1994 and Odense since 1997. Measurements of benzene, CO and NO~ from these two locations were analysed using the Operational Street Pollution Model (OSPM) and trends in the actual emissions of these pollutants were determined. It is shown that the decrease in both the concentration levels and in the emissions was significantly larger for benzene than for CO and NOx. The decreasing trends of NOx and CO could be explained by the increasing fraction of petrol-fuelled vehicles with three way catalysts (TWC). The much steeper decreasing trend for benzene can most likely be attributed to a combination of the effect of the increasing share of the TWC vehicles and a simultaneous reduction of benzene content in Danish petrol. The reduction of benzene concentrations and emissions is observed despite that the total amount of aromatics in petrol has increased slightly in the same period.

Since October 1998 two DOAS instruments were installed at the level of the first floor and at the top of a building located in St. Petersburg at Pestelya Street. The collected data covers the time period of December 1998-March 2001, and include concentrations of benzene, toluene, NO and NO 2 , ozone and SO 2. There is also an additional information about the traffic intensity and meteorological conditions. The results of the analysis of this data set, using the OSPM model, are presented here with the goal to understand the features of the air pollution dispersion in this street canyon and to analyse the information about the emission factors of the vehicles. In particular, the model results are used for the solution of the inverse problem of reconstructing the emission factors from measured concentrations. The results obtained indicate that most of the concentrations are well inside the Russian standards with the only exception of NO 2 (mean and 98-th percentile are equal to 57.8 and 119.2 µg m −3 for the street level). The same values for benzene are 18.5 and 62.6, respectively. Emission estimates show that there is a possibility that the NO x and benzene basic emission factors recommended by the Russian national guidelines could result in overestimating the traffic emissions. These considerations are supplemented with the model sensitivity tests carried out in connection with the problem of predictability of NO 2 concentrations in the street canyon. Tests indicate that NO 2 concentrations are not very sensitive to NO x emissions because of the usually low urban background ozone levels.

Background Traffic emissions including diesel engine exhaust are associated with increased respiratory and cardiovascular morbidity and mortality. Controlled human exposure studies have demonstrated impaired vascular function after inhalation of exhaust generated by a diesel engine under idling conditions. Objectives To assess the vascular and fibrinolytic effects of exposure to diesel exhaust generated during urban-cycle running conditions that mimic ambient &#39;real-world&#39; exposures. Methods In a randomised double-blind crossover study, eighteen healthy male volunteers were exposed to diesel exhaust (approximately 250 μg/m3) or filtered air for one hour during intermittent exercise. Diesel exhaust was generated during the urban part of the standardized European Transient Cycle. Six hours post-exposure, vascular vasomotor and fibrinolytic function was assessed during venous occlusion plethysmography with intra-arterial agonist infusions. Measurements and Main Results Forearm b...

Roadside air quality and vehicle emission are important and challenging issues in urban air quality management which need to be adequately characterized. This study involves designing a monitoring program that produces suitable data to determine the on-road hourly fleet emission and emission factors of individual vehicles in a street canyon. Simultaneous hourly monitoring of roadside gaseous pollutants (both windward and leeward sides), traffic volume and speed, and wind in a busy street of Bangkok was conducted in the rainy season when traffic emission was predominant in the city. Higher pollutant concentrations often occurred at midday (11:00 to 14:00h) when higher traffic density (3700-3800vehicles h − 1 , weekdays) was observed. The levels of toluene and xylenes found in this study are higher than the roadside levels reported in other Asian cities. Hourly maximum concentrations reached 258ppb for toluene, 51ppb for m,p-xylenes, 15ppb for o-xylene, 526ppb for NO x , and 10.5ppm for CO. Hourly monitoring data during the periods when the street canyon effects were pronounced were selected for determination of the fleet hourly emission and vehicle emission factors by back calculation using a street canyon model (Operational Street Pollution Model). The average fleet hourly emission at daytime of NO x (6.2kg km − 1 h − 1), CO (54kg km − 1 h − 1), toluene (2.1kg km − 1 h − 1), m,p-xylenes (0.73kg km − 1 h − 1) and o-xylene (0.27kg km − 1 h − 1) did not vary much. However, the emission rates were substantially reduced at nighttime following the traffic pattern. The obtained pollutant emission factors varied within each group of vehicles with the average values agreed reasonably with the chassis dynamometer results for NO x but somewhat higher for CO and TX. The model estimated results are, however, considered to better represent the real driving conditions in the street at the average vehicle travel speed of around 20km h − 1. A statistical sampling design is proposed to generate necessary data for the traffic emission inventory in a city.

The intake fraction (iF) has been defined as the integrated incremental intake of a pollutant released from a source category or region summed over all exposed individuals. In this study we evaluated the iFs in the population of Europe for emissions of anthropogenic primary fine particulate matter (PM 2.5) from sources in Europe, with a more detailed analysis of the iF from Finnish sources. Parameters for calculating the iFs include the emission strengths, the predicted atmospheric concentrations, European population data, and the average breathing rate per person. Emissions for the whole of Europe and Finland were based on the inventories of the European Monitoring and Evaluation Programme (EMEP) and the Finnish Regional Emission Scenario (FRES) model, respectively. The atmospheric dispersion of primary PM 2.5 was computed using the regional-scale dispersion model SILAM. The iFs from Finnish sources were also computed separately for six emission source categories. The iFs corresponding to the primary PM 2.5 emissions from the European countries for the whole population of Europe were generally highest for the densely populated Western European countries, second highest for the Eastern and Southern European countries, and lowest for the Northern European and Baltic countries. For the entire European population, the iF values varied from the lowest value of 0.31 per million for emissions from Cyprus, to the highest value of 4.42 per million for emissions from Belgium. These results depend on the regional distribution of the population and the prevailing long-term meteorological conditions. Regarding Finnish primary PM 2.5 emissions, the iF was highest for traffic emissions (0.68 per million) and lowest for major power plant emissions (0.50 per million). The results provide new information that can be used to find the most cost-efficient emission abatement strategies and policies.

Sixty moss samples were taken along transects of nine roads in Austria. The concentrations of 17 elements in four moss species were determined. There was a high correlation between several elements like Cu/Sb (0.906), Ni/Co (0.897) or Cr/V (0.898), indicating a common traffic-related source. Enrichment factors were calculated, showing highest enrichment levels for: Cr, Mo, Sb, Zn, As, Fe, V, Cu, Ni, and Co. For these elements, road traffic has to be assumed as a source, which is confirmed by a significant negative correlation of the concentrations in mosses to the distance from the road for most of these metals. The rate of decrease followed a log-shaped curve at most of the investigated transects, although the decline cannot be explained by a single model. Multiple regression analysis highlighted traffic density, distance from and elevation of the road as the most influencing factors for the deposition of the investigated elements. Heavy duty vehicles (HDVs) and light duty vehicles (LDVs) showed different patterns. A comparison of sites likely to be influenced by traffic emissions with average values for the respective regions showed no significant differences for road distances of more than 250 m. Nevertheless, at heavily frequented roads, raised deposition of some elements was found even at a distance of 1000 m.

Data sets from street canyons in Stockholm, Berlin and London are used to investigate the performance of the Gaussian model ADMS-Roads 1 and the Lagrangian model LASAT 2 and the impact of different meteorological input, flow schemes and NO-NO 2 conversion schemes. ADMS-Roads tends to under-predict NO x concentrations. Nevertheless, the more complex Lagrangian model is not always in better agreement with the observations. LASAT with a simpler flow scheme leads to higher concentrations of NO x than the more complex DMK scheme in Stockholm and Berlin. Model runs based on time-series of stability classes render in several cases better results than those with constant neutral conditions. Two NO-NO 2 conversion schemes are used. The scheme after Romberg performs better for LASAT in most of the cases while the Derwent approach is more successful for ADMS-Roads. Although point to point correlations between model results and measurements are generally weak, both dispersion models are quite successful in predicting average values, maximum values as well as the occurrence of exceedances of threshold limits within the street canyons.

A variable-path-length diffusive sampler for the determination of atmospheric ammonia was developed and tested. Polyethylene was found to be the best material for the construction of the sampler, while a glass body sampler of similar design yielded unreliable results; phosphorous acid was the best collecting medium. The low level of the field blanks and the high operative capacity make this device able to operate in a very wide loading range (0.3-100 mg); the possibility to vary the length of the diffusive pathway allows a further increase of the detectable concentration range (0.1-125 mg m À3 during a 1-month exposure). Reproducibility is better than 5% and the comparison with reference denuders demonstrated a good accuracy of the method (deviation lower than 5%). The deployment of these samplers in some field campaigns carried out in Rome allowed us to confirm the close link between ammonia concentration and traffic emission and to get an insight into the spatial variability of this pollutant.

This paper describes a novel methodology for evaluating the extent to which petrol stations affect their surroundings. The method is based on the fact that the ratio of the concentrations of aliphatic and aromatic hydrocarbon pollutants in the air of the petrol stations and their surroundings (basically determined by vapor emissions from unburned gasoline) differs from the ratio found in urban air, which is mainly influenced by traffic emissions. Bearing this in mind, the spatial limit of influence of petrol stations in any direction would be the first point, moving away from the station, where the ratio becomes equal to the urban background ratio. Application of the methodology involves multipoint measuring campaigns of the air at the studied petrol station and built-up area in general and processing the data with software capable of providing isoconcentration contours. The procedure should help local authorities in terms of land management, so that a "belt" can be established around petrol stations where housing or vulnerable populations and activities such as those in schools, hospitals and community centers should be restricted.

A methodology for quantifying areas of spatial representativeness of air quality monitoring station is here proposed, exploiting the wide spatial and temporal coverage of chemical transport models results. The method is based on the analysis of time series of model concentrations, extracted at monitoring sites and around, by means of a Concentration Similarity Function (CSF). The method was tested on AMS-MINNI model results, covering Italy and three reference years (2003, 2005, 2007), for assessing the spatial representativeness of PM2.5 and O 3 rural background monitoring stations. The CSF methodology shows good performances in describing both the extension and the shape of representativeness areas, taking into account the difference between pollutants and the dependence on averaging time and temporal interval of concentration data. Results show a large variability in the size and shape of the selected stations in Italy, ranging from 220 to 4500 km 2. This confirms the importance of carrying out adhoc analyses on monitoring stations, as general a priori classifications and qualitative assessments of spatial representativeness are not able to fully capture the complexity of different territorial contexts.

Black carbon (BC) is a significant component of atmospheric particulate matter, especially in areas affected by combustion emissions. Despite the fact that air pollution is a great concern in Vietnam, there are no studies on the level of BC in the outdoor and indoor environment. In this exploratory study, an assessment of urban BC concentrations was conducted through monitoring of both outdoor and indoor BC concentrations in three households and one working office at different locations across Hanoi. PM and meteorology data were also obtained for this monitoring period to evaluate the association between them and the outdoor BC concentration. Overall, the mean indoor and mean outdoor BC concentrations by 30 second-logs for the monitoring period were 4.42 μg/m and 4.89 μg/m, respectively. Time-series analysis of paired indoor and outdoor BC concentrations suggested that indoor BC level was usually influenced by outdoor BC level (r = 0.78, p &lt; 0.001). In this study, we observed a s...

INTRODUCTION The deterioration of air quality in urban areas is a cause of serious concern in practically all developed countries. The full application, enforcement, and implementation of the existing environmental legislation have become a worrying issue for national and ...

The size distribution of ambient air particles and associated organic pollutants, such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) including hexachlorocyclohexanes (HCHs), DDT and metabolites, etc., was investigated at a trafficimpacted site of Thessaloniki, Greece. Investigation took place during wintertime of 2006 at two heights above ground: at the street level (1.5 m) and at the rooftop level (15 m). Size-resolved samples (<0.95 mm, 0.95-1.5 mm, 1.5-3 mm, 3-7.5 mm and >7.5 mm) were concurrently collected from the two height levels using five-stage high volume cascade impactors. At both heights, particle mass exhibited bimodal distribution with peaks in the 0.95-1.5 mm and the 3-7.5 mm size fractions, whereas most organic pollutants exhibited one peak at 0.95-1.5 mm. Apart from the 0.95-1.5 mm fraction, particle concentrations of all size ranges were significantly higher at the street level than at the rooftop as a result of more intensive vehicular emissions and road dust resuspension. On the contrary, the concentrations of most organic pollutants did not differentiate significantly between the two elevations.

We describe the EMITEMA-EIM atmospheric emission model, and how it has been used along with CORINAIR emission factors to estimate the annual emissions in the Barcelona area in 1990. The study area is a 39 x 39 km 2 square with a high population density and important industrial activities. The space and time resolution of the emissions is, respectively, 1 km 2 and 1 h. The pollutants considered were NO x, CO, SO2, particles, methane and several VOCs (alkanes, alkenes, aromatics and aldehydes). The emission sources studied were road traffic, air traffic, industrial activities, gas stations, domestic heating and biogenic emission from forests. Methodologies for each of these sources are described in this paper. Finally, we present and analyse the results.

Since October 1998 two DOAS instruments were installed at the level of the first floor and at the top of a building located in St. Petersburg at Pestelya Street. The collected data covers the time period of December 1998-March 2001, and include concentrations of benzene, toluene, NO and NO 2 , ozone and SO 2. There is also an additional information about the traffic intensity and meteorological conditions. The results of the analysis of this data set, using the OSPM model, are presented here with the goal to understand the features of the air pollution dispersion in this street canyon and to analyse the information about the emission factors of the vehicles. In particular, the model results are used for the solution of the inverse problem of reconstructing the emission factors from measured concentrations. The results obtained indicate that most of the concentrations are well inside the Russian standards with the only exception of NO 2 (mean and 98-th percentile are equal to 57.8 and 119.2 µg m −3 for the street level). The same values for benzene are 18.5 and 62.6, respectively. Emission estimates show that there is a possibility that the NO x and benzene basic emission factors recommended by the Russian national guidelines could result in overestimating the traffic emissions. These considerations are supplemented with the model sensitivity tests carried out in connection with the problem of predictability of NO 2 concentrations in the street canyon. Tests indicate that NO 2 concentrations are not very sensitive to NO x emissions because of the usually low urban background ozone levels.

Air pollution represents a serious risk not only to environment and human health, but also to historical heritage. In this study, air pollution of the Oporto Metropolitan Area and its main impacts were characterized. The results showed that levels of CO, PM10 and SO2 have been continuously decreasing in the respective metropolitan area while levels of NOx and NO2 have not changed significantly. Traffic emissions were the main source of the determined polycyclic aromatic hydrocarbons (PAHs; 16 PAHs considered by U.S. EPA as priority pollutants, dibenzo[a,l]pyrene and benzo[j]fluoranthene) in air of the respective metropolitan area. The mean concentration of 18 PAHs in air was 69.9±39.7 ng m−3 with 3-4 rings PAHs accounting for 75% of the total ΣPAHs. The health risk analysis of PAHs in air showed that the estimated values of lifetime lung cancer risks considerably exceeded the health-based guideline level. Analytical results also confirm that historical monuments in urban areas act as passive repositories for air pollutants present in the surrounding atmosphere. FTIR and EDX analyses showed that gypsum was the most important constituent of black crusts of the characterized historical monument Monastery of Serra do Pilar classified as "UNESCO World Cultural Heritage". In black crusts, 4-6 rings compounds accounted approximately for 85% of ΣPAHs. The diagnostic ratios confirmed that traffic emissions were the major source of PAHs in black crusts; PAH composition profiles were very similar for crusts and PM10 and PM2.5.

Air pollution due to motor vehicles is a worrying issue, in particular in the urban environment, all the more as a number of pollutants such as benzene and PAH are known to have carcinogenic effects. Epidemiological studies seem to be required, so a cumulated score of exposure must be developed. A correlation with pathology should be investigated. The calculation of an index of exposure to motor vehicle-related pollution requires a good assessment of pollutant emissions and a precise knowledge of pollutant transfer mechanisms by advection and spreading in built-up areas. In this study, it is proposed to use current theoretical and experimental knowledge to develop a calculation algorithm for this index. The following issues will be addressed in the presentation: an analysis of epidemiological requirements and of constraints of data acquisition using questionnaire surveys; a model for assessing, for each residential area, the average annual concentration of gaseous pollutants from motor vehicles. It will consider the environment geometry, traffic emissions and wind distributions. The model CALINE3 is used for open areas near roads and highways and the Danish model OSPM is introduced for street canyon environments.

The detection of high ozone levels over large inland areas in Israel during the early, mid and late summer triggered an analysis of air mass back-trajectories. This, in turn, pointed to the transportation system in the metropolitan coastal Tel Aviv region as the possible origin of the ozone's precursors. To link the daily dynamics of rush hour transportation emissions to inland air pollution, in general, and airborne ozone measurements, in particular, an interdisciplinary modeling system was established. The simulations of transportation-to-inland air pollution integrated transportation, emission factor, atmospheric, transport/diffusion, and photochemical models. The modeling results elucidated a spatial and temporal overlap between the ozone precursors and ozone production. The model simulations indicated east to southeasterly dispersion of the pollution cloud. The results agreed well with both spatial and temporal ozone levels as recorded by aircraft over central Israel, as well as with ground-based monitoring station observations. The impact of the Tel Aviv metropolitan area as well as the Gaza Strip, as pivotal coastal transportation sources for inland air pollution in general and ozone formation in particular, is discussed. The synoptic analysis identified the conditions prevailing when elevated air pollution, and especially high ozone levels, exists over central Israel. The analysis showed that this season features a shallow mixed layer and weak zonal flow, which leads to poor ventilation rates and inhibit efficient dispersion of this secondary pollutant. These poor ventilation rates result in the slow transport of ozone precursors, enabling their photochemical transformation under intense solar radiation during their travel from the coast inland. Under these conditions, model results showed that traffic emissions during the morning rush hour from the Tel Aviv metropolitan area contribute about 60% to the observed ozone concentrations.

Focussed aircraft measurements have been carried out over the eastern North Atlantic to search for signals of air traffic emissions in the flight corridor region. Observations include NO, NO2, HNO3, SO2, 03, H20, total condensation nuclei (CN), and meteorological parameters. A flight pattern with constant-altitude north-south legs across the major North Atlantic air traffic tracks was flown. Signatures of air traffic emissions were clearly detected for NO•, SO2, and CN with peak concentrations of 2 ppbv, 0.25 ppbv, and 500 cm-3, respectively, exceeding background values by factors of 30 (NO•), 5 (SO2), and 3 (CN). The observed NO•, SO2, and CN peaks were attributed to aircraft plumes based on radar observations of the source air traffic and wind measurements. Major aircraft exhaust signatures are due to relatively fresh emissions, i.e., superpositions of 2 to 5 plumes with ages of about 15 min to 3 hs. The observed plume peak concentrations of NO• compare fairly well with concentrations computed with a Gaussian plume model using horizontal and vertical diffusivities as obtained by recent large-eddy sixnulations, measured vertical wind shear, and the corridor air traffic information. For the major emission signatures a mean CN/NO• abundance ratio of 300 cm-appbv-1 was measured corresponding to an emission index (EI) of about 101• particles per 1 kg fuel burnt. This is higher than the expected soot particle EI of modern widebodied aircraft. For the most prominent plumes no increase of HNO3 concentrations exceeding variations of background values was observed. This indicates that only a small fraction of the emitted NO• is oxidized in the plumes within a timescale of about 3 hs for the conditions of the measurements. nonlinear chemistry the 03 formation efficiency from additional NO• input is dependent on the existing NO• lInstitut fiJr Physik der Atmosphfire, Deutsche Forschungsanstalt for Luft-und Raumfahrt,

We describe the EMITEMA-EIM atmospheric emission model, and how it has been used along with CORINAIR emission factors to estimate the annual emissions in the Barcelona area in 1990. The study area is a 39 x 39 km 2 square with a high population density and important industrial activities. The space and time resolution of the emissions is, respectively, 1 km 2 and 1 h. The pollutants considered were NO x, CO, SO2, particles, methane and several VOCs (alkanes, alkenes, aromatics and aldehydes). The emission sources studied were road traffic, air traffic, industrial activities, gas stations, domestic heating and biogenic emission from forests. Methodologies for each of these sources are described in this paper. Finally, we present and analyse the results.

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We developed and tested a methodology to extract both the size-segregated source apportionment of atmospheric aerosol and the size distribution of each detected element. The experiment is based on the parallel use of a standard low-volume sampler to collect Particulate Matter (PM) and an Optical Particle Counter (OPC). The approach is complementary to size-segregated PM sampling, and it was tested versus a 12-stage cascade impactor. Samples were collected inside the urban area of Genoa (Italy) and their elemental composition was measured by Energy Dispersive-X Ray Fluorescence (ED-XRF). Positive Matrix Factorization (PMF) was applied to time series of elemental concentrations to identify major PM sources, and both PM mass concentration and size-segregated particle number concentration were apportioned. Source profiles and temporal trends extracted by PMF were analyzed together with the OPC data to obtain the size distribution for several elements. The new methodology proved to be reliable for the PM apportionment as well as in providing the elemental concentrations in PM10, PM2.5, and PM1 (PM with aerodynamic diameter, D ae < 10, 2.5, and 1 mm, respectively). The elemental size distributions are in good agreement with those obtained by the cascade impactor for several elements but some discrepancies, in particular for traffic emissions, are stressed and discussed in the text. The new methodology has two main advantages: it only requires standard semi-automatic sampling equipment and compositional analysis and it provides size-segregated information averaged over quite long periods (typically several months). This is particularly important since campaigns with cascade impactors are generally laborious and thus limited to short periods.

Emerging evidence suggests that short episodes of high exposure to air pollution occur while commuting. These events can result in potentially adverse health effects. We present a quantification of the exposure of car passengers and cyclists to Particulate Matter (PM). We have simultaneously measured concentrations (PNC, PM2.5 and PM10) and ventilatory parameters (minute ventilation (VE), breathing frequency and tidal volume) in three Belgian locations (Brussels, Louvain-la-Neuve and Mol) for 55 persons (38 male and 17 female). Subjects were first driven by car and then cycled along identical routes in a pairwise design. Concentrations and lung deposition of PNC and PM mass were compared between biking trips and car trips. Mean bicycle/car ratios for PNC and PM are close to 1 and rarely significant. The size and magnitude of the differences in concentrations depend on the location which confirms similar inconsistencies reported in literature. On the other hand, the results from this study demonstrate that bicycle/car differences for inhaled quantities and lung deposited dose are large and consistent across locations. These differences are caused by increased VE in cyclists which significantly increases their exposure to traffic exhaust. The VE while riding a bicycle is 4.3 times higher compared to car passengers. This aspect has been ignored or severely underestimated in previous studies. Integrated health risk evaluations of transport modes or cycling policies should therefore use exposure estimates rather than concentrations.

Background Traffic emissions including diesel engine exhaust are associated with increased respiratory and cardiovascular morbidity and mortality. Controlled human exposure studies have demonstrated impaired vascular function after inhalation of exhaust generated by a diesel engine under idling conditions. Objectives To assess the vascular and fibrinolytic effects of exposure to diesel exhaust generated during urban-cycle running conditions that mimic ambient &#39;real-world&#39; exposures. Methods In a randomised double-blind crossover study, eighteen healthy male volunteers were exposed to diesel exhaust (approximately 250 μg/m3) or filtered air for one hour during intermittent exercise. Diesel exhaust was generated during the urban part of the standardized European Transient Cycle. Six hours post-exposure, vascular vasomotor and fibrinolytic function was assessed during venous occlusion plethysmography with intra-arterial agonist infusions. Measurements and Main Results Forearm b...

The main objective of the study is to quantify the mass concentration exposure levels of fine trafficgenerated particles (PM 2.5) at various heights of typical multi-storey public housing buildings located in close proximity, i.e. within 30 m and along a busy major expressway in Singapore. The secondary objective is to compare the potential health risks of occupants in the buildings, associated with inhalation exposure of fine traffic-generated particulate matter, based on estimated dose rates and the lowest observed adverse effect levels (loael) at the various floors of these buildings. Two typical public housing buildings, both naturally ventilated residential apartment blocks, of point block configuration (22-storey) and slab block configuration (16-storey) were selected for the study. Particulate samples were collected for both mass and chemical analysis (OC/EC ratio) at three representative floors: the lower, the mid, and upper floors of the buildings. Key meteorological parameters such as wind speed, wind direction, ambient temperature, and relative humidity were also concurrently measured at the sampling locations. For the potential health risk analysis, the occupants have been divided into four age categories namely, infants, children (1 year), children (8-10 years) and adults. The analysis takes into account age-specific breathing rates, body weights for different age categories. Experimental results explicitly showed that PM 2.5 mean particle mass concentration was highest at the midfloors of both buildings when compared to those measured at upper and lower floors during a typical day. Although the lower floors were closest to traffic emissions, the mean particle mass concentration was lower there than that at the midfloors, which could presumably be due to the interception of PM 2.5 particles by tree leaves or the inflow of clean and drier air from higher altitude with lower aerosol burden mixing with the traffic-polluted air at the lower levels thus lowering the concentration at the lower floors similar to induced chimney effect or both. The upper floors had the least fine particulate matter mass concentration due to dilution following pronounced mixing of traffic-polluted air with ambient air. The only difference between both blocks is that at corresponding floors, the mass concentration levels for slab block is much higher than that of point block. This could be attributed to the configuration of the blocks. Observational data show the slab block tends to slow down the approaching wind thus allowing the accumulation of the fine traffic-generated particulate matter in front of the building. For point block, the HR values at the mid and lower floors suggest that occupants living in these floors experience 1.81 and 1.34 times more health risk, respectively, in contracting respiratory diseases when compared to those living at the upper floors for all age categories. Similarly, for the slab block, occupants living in the mid and lower floors had 1.62 and 1.28 times more risk, respectively, in contracting respiratory diseases when compared to those living at the upper floors for all age categories.

In this paper, variations of nitric oxide (NO), nitrogen dioxide (NO 2), oxides of nitrogen (NOx), ozone (O 3) and total oxidant (O X) concentration in ambient air of Kathmandu valley are presented. O 3 behavior during weekdays, weekends and bandhas (general strike) is analyzed and the mechanism related to it is discussed. The increased NO 2 /O X ratio with increasing NOx concentration and the inverse relation between NOx and O 3 imply that the residual O 3 remaining after the NO-NO 2-O 3 reaction chain controlled O 3 concentration in the valley atmosphere and the radical channel was likely to have a minor contribution. The higher positive correlation coefficient for O 3 variation during weekdays and bandhas, weekdays and weekends suggests common sources for the weekends and bandhas O 3 variation. The higher O 3 concentration during weekends and bandhas compared to weekdays was due to less destruction of O 3. Enhanced reduction in traffic emission levels, enforcement of stringent emission standards within the valley and the surroundings may help to address the O 3 problem in the valley atmosphere.

A study of particulate laden polyaromatic hydrocarbon was conducted at 13 selected locations in a 10 km radial distance of a proposed site for a grass root level industry. Suspended particulate matter samples were continuously monitored for 24 h over a period of 3 months. The Polyaromatic Hydrocarbons (PAHs) were extracted from the particulate samples and analysed using Gas Chromatograph-Mass Spectrometer. Limit of Quantification was also established for individual PAHs. Coal combustion and traffic emission were the major contributors for PAHs in the region. The relative contribution of 2, 3, 4, 5, and 6 ring PAHs in particulates of different sampling sites was also investigated and it is observed that 4 ring (29.76%) and 5 ring (29.06%) compounds are prominent in the particulates measured in the region.

Car traffic is one of the main anthropogenic aerosol sources in modern cities. The characterization of these emissions is important for describing the quality of urban air. Measurements in a street canyon in a German urban area were made. Maximum number concentrations occurred during morning hours from Monday to Friday when the traffic density is highest. The maximum of the number size distribution measured during rush hour near a busy city street was at a particle diameter of 15 nm: This differs significantly from size distributions directly measured in vehicle exhaust (vehicles placed on chassis dynamometers used for vehicle emissions certification), typically about 50 nm: The size distributions measured in the urban area depended on the distance to the nearest road. With increasing distance, the maximum of the size distribution increased, and the total number concentration decreased. This seems to be a result of particle growth due to processes such as coagulation and condensation, and dilution with the surrounding air. To clarify the transformation of the particle number size distributions measured in a street canyon into the urbanair background, a sectional aerosol model was used to calculate the evolution of the number size distribution, and included the effect of condensation, coagulation, dilution, and continuous entrainment of freshly emitted particles yielding good agreement with measurements.

A new setup has been developed and built to measure number size distributions of exhaust particles and thermodynamic parameters under real traffic conditions. Measurements have been performed using a diesel and a gasoline passenger car driving with different speeds and engine conditions. Significant number of nucleation mode particles was found only during high load conditions, i.e. high car and engine speeds behind the diesel car. The number concentration of soot mode particles varied within a factor of two for different engine conditions while the concentration of nucleation mode particles varied up to two orders of magnitude. The results show that roadside measurements are still quite different from those behind the tailpipe. Beside dilution transformation processes within the first meter behind the tailpipe also play an important role, such as nucleation and growth. Emission factors were calculated and compared with those obtained by other studies. Emission factors for particles larger than 25 nm (primary emissions) varied within 1.1 Â 10 14 km À1 and 2.7 Â 10 14 km À1 for the diesel car and between 0.6 Â 10 12 km À1 and 3.5 Â 10 12 km À1 for the gasoline car. The advantage of these measurements is the exhaust dilution under atmospheric conditions and the size-resolved measurement technique to divide into primary emitted and secondary formed particles.

A correct description of fine (diameter <1 µm) and ultrafine (<0.1 µm) aerosol particles in urban areas is of interest for particle exposure assessment but also basic atmospheric research. We examined the spatio-temporal variability of atmospheric aerosol particles (size range 3-800 nm) using concurrent number size distribution measurements at a maximum of eight observation sites in and around Leipzig, a city in Central Europe. Two main experiments were conducted with different time span and number of observation sites (2 years at 3 sites; 1 month at 8 sites). A general observation was that the particle number size distribution varied in time and space in a complex fashion as a result of interaction between local and far-range sources, and the meteorological conditions. To identify statistically independent factors in the urban aerosol, different runs of principal component (PC) analysis were conducted encompassing aerosol, gas phase, and meteorological parameters from the multiple sites. Several of the resulting PCs, outstanding with respect to their temporal persistence and spatial coverage, could be associated with aerosol particle modes: a first accumulation mode ("droplet mode", 300-800 nm), considered to be the result of liquid phase processes and far-range transport; a second accumulation mode (centered around diameters 90-250 nm), considered to result from primary emissions as well as aging through condensation and coagulation; an Aitken mode (30-200 nm) linked to urban traffic emissions in addition to an urban and a rural Aitken mode; a nucleation mode (5-20 nm) linked to urban traffic emissions; nucleation modes

This paper describes a novel methodology for evaluating the extent to which petrol stations affect their surroundings. The method is based on the fact that the ratio of the concentrations of aliphatic and aromatic hydrocarbon pollutants in the air of the petrol stations and their surroundings (basically determined by vapor emissions from unburned gasoline) differs from the ratio found in urban air, which is mainly influenced by traffic emissions. Bearing this in mind, the spatial limit of influence of petrol stations in any direction would be the first point, moving away from the station, where the ratio becomes equal to the urban background ratio. Application of the methodology involves multipoint measuring campaigns of the air at the studied petrol station and built-up area in general and processing the data with software capable of providing isoconcentration contours. The procedure should help local authorities in terms of land management, so that a "belt" can be established around petrol stations where housing or vulnerable populations and activities such as those in schools, hospitals and community centers should be restricted.

This paper describes the experimental methodology and basic results of the PEOPLE project (Population Exposure to Air Pollutants in Europe). Simultaneous diffusive measurements of outdoor, indoor and human exposure benzene concentrations were made during one day campaigns. Six cities were assessed, namely:

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It has recently been recognized that air and noise pollution constitutes an extended problem over the densely populated city of Buenos Aires. Tra$c emissions are of paramount concern, especially along narrow and main tra$c arteries. In spite of these considerations, few systematic studies have been undertaken to evaluate the air quality in the metropolitan area of the city. In 1996, concentrations of carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO) and ozone (O) were simultaneously measured for the "rst time using a continuous monitoring station. This station was placed in a building at Belgrano Avenue, which is a heavy tra$c street in the downtown area of the city (Bogo et al., Atmospheric Environment 33 (1999) 2587. In this work, we analyze the dependence of the measured primary pollutants, CO and the mixture of nitrogen oxides (NO V), with meteorological conditions, tra$c emissions and monitoring location. We compare the registered values with the results obtained from modeling the dispersion of the pollutants emitted from mobile and area sources. We also discuss the relevance of street canyon e!ects compared with background concentrations of these pollutants.

Air and soil pollution from traffic has been considered as a critical issue to crop production and food safety, however, few efforts have been paid on distinguish the source origin of traffic-related contaminants in rice plant along highway. Therefore, we investigated metals (Pb, Cd, Cr, Zn and Cu) concentrations and stable Pb isotope ratios in rice plants exposed and unexposed to highway traffic pollution in Eastern China in 2008. Significant differences in metals concentrations between the exposed and unexposed plants existed in leaf for Pb, Cd and Zn, in stem only for Zn, and in grain for Pb and Cd. About 46% of Pb and 41% of Cd in the grain were attributed to the foliar uptake from atmosphere, and there were no obvious contribution of atmosphere to the accumulations of Cr, Zn and Cu in grain. Except for Zn, all of the heavy metals in stem were attributed to the root uptake from soil, although significant accumulations of Pb and Cd from atmosphere existed in leaf. This indicated that different processes existed in the subsequent translocation of foliar-absorbed heavy metals between rice organs. The distinct separation of stable Pb isotope ratios among rice grain, leaf, stem, soil and vehicle exhaust further provided evidences on the different pathways of heavy metal accumulation in rice plant. These results suggested that further more attentions should be paid to the atmospheric deposition of heavy metals from traffic emission when plan crop layout for food safety along highway.

A~tmct-A model is developed for the spatial and temporal evaluation of traffic emissions in metropolitan areas based on sparse measurements. All traffÉc data available are fully employed and the pollutant emissions are determined with the highest precision possible. The main roads are regarded as line sources of constant traffic parameters in the time interval considered. The method is flexible and allows for the estimation of distributed small traffic sources (non-line/area sources). The emissions from the latter are assumed to be proportional to the local population density as well as to the traffic density leading to local main arteries. The contribution of moving vehicles to air pollution in the Greater Athens Area for the period 1986-1988 is analysed using the proposed model. Emissions and other related parameters are evaluated. Emissions from area sources were found to have a noticeable share of the overall air pollution.

and Zn in road dust particles at seven sites in the Delta region have been investigated using atomic absorption spectroscopy (AAS). Results showed that samples were highly contaminated with Cd, Pb, Sn and Zn and moderately contaminated with As, Se, Ba and Cu when compared to the average crustal background concentrations of metals. The output of the principle component analysis revealed that Al, Fe, Be and Mn were predominantly driven from natural sources and that all the other metals were anthropogenically driven from industrial activities (As, Ba, Cd, Cr, Cu, Se, and Sn) and traffic emissions (Pb, Ni and V). Results of the applied risk assessment indicated that the higher risk of occurrence of adverse non-carcinogenic health effects is associated with the exposure of children to Al, Fe, As, Cr, Pb and Zn via the ingestion pathway and that carcinogenic health effects are not expected to occur from the exposure to metals in the road dust of the Delta region. However, given the large uncertainties associated with the estimates of toxicity values and exposure factors, and the absence of site-specific biometric factors, these results should be regarded as a screening data. Further research should be undertaken before any definite conclusions regarding potential health effects are drawn.

In urban conditions, car exhaust gases are often emitted inside poorly ventilated street canyons. One may suppose however that moving cars can themselves produce a certain ventilation effect in addition to natural air motions. Such ventilation mechanism is not sufficiently studied so far. A similarity criterion relating the vehicle-and wind-induced components of turbulent motion in an urban street canyon was proposed in 1982 by E. J. Plate for wind tunnel modelling purposes. The present study aims at further evaluation of the criterion and its applicability for a variety of wind and traffic conditions. This is accomplished by joint analyses of data from numerical simulations and wind tunnel measurements.

In this paper we present a model-based traffic flow control approach to improve both traffic flow and emissions in a traffic network. A model predictive control (MPC) is implemented using a microscopic car-following traffic flow model and an average-speed-based emission model. We consider reduction of total time spent (TTS) and total emissions (TE) as performance measures of the control strategy. Moreover, with the help of simulations we illustrate that a traffic control strategy, particularly an MPC strategy, aiming at the reduction of the TTS does not necessarily reduce the level of emissions. In particular, when the traffic flow is congested, we demonstrate that a traffic control strategy that addresses TTS (or improvement of the traffic flow) alone can cause an increment in the level of emissions and vice versa. Therefore, in this paper we explain how to integrate both requirements so that a balanced trade-off is obtained.

In this contribution we show the integration of a mesoscale air quality model OPANA with the ISCST3 Gaussian model (EPA) in order to analyze the impact of different emission sources and particularly the traffic emission into the different gridboxes which define the OPANA Eulerian structure. The application is done over the Madrid (Spain) regional area with 80 x 100 km and gridboxes of about 5 km. Thousands of Gaussian runs over interested gridboxes are executed in order to simulate the traffic emissions from each gridbox. Each mobile unit is represented by a Gaussian point emitter. Input meteorological variables for the ISCST3 are taken from the OPANA mesoscale air quality model. Results shows that it is possible to model the impact of traffic emissions over each gridbox. A short comparison with air quality monitoring in each gridbox is also shown.