Road Dust Emissions Research Articles

Studies of some measures to reduce road dust emissions from paved roads in Scandinavia

In this paper we present quantitative assessments of different measures to reduce the PM10 levels along streets in Scandinavian cities based on tests in Stockholm. The effect of the use of studded tyres on concentrations in a street canyon has been quantitatively assessed using monitoring data. A 10% decrease in the fraction of studded tyres was estimated to reduce the weekly average street canyon PM10 levels (due to local road abrasion) by about 10 μg m −3 if only daytime and dry street conditions were considered. These results are obtained by correlating the increase in PM10 levels during autumn with the increased use of studded tyres. Since the share of studded tyres is around 75% in Stockholm during wintertime, the peak springtime PM10 levels that occur during dry road conditions would be substantially lower if the use of studded tyres were regulated. Intense sweeping or washing of the pavements resulted in marginal reductions (<10%) and will have no important influence on the PM10 levels with the methodologies and working machineries tested here. Application of calcium magnesium acetate (CMA, Ice Away, as 25% water solution) on the road surface of a highway during dry conditions resulted in an average reduction of around 35% in the daily PM10 averages. The most efficient way to reduce PM10 levels in the long-term and for a large area is to reduce the use of studded tyres, while application of CMA may be efficient to reduce peak levels, which frequently occur during dry road conditions in spring.

Seasonal Variations of PM10 and TSP in Residential and Industrial Sites in an Urban Area of Kolkata, India

The objective of the study is to investigate seasonal and spatial variations of PM10 (particulate matter with aerodynamic diameter less than or equal to 10 microm) and TSP (total suspended particulate matter) of an Indian Metropolis with high pollution and population density from November 2003 to November 2004. Ambient concentration measurements of PM10 and TSP were carried out at two monitoring sites of an urban region of Kolkata. Monitoring sites have been selected based on the dominant activities of the area. Meteorological parameters such as wind speed, wind direction, rainfall, temperature and relative humidity were also collected simultaneously during the sampling period from Indian Meteorological Department, Kolkata. The 24 h average concentrations of PM10 and TSP were found in the range 68.2-280.6 microg/m3 and 139.3-580.3 microg/m3 for residential (Kasba) area, while 62.4-401.2 microg/m3 and 125.7-732.1 microg/m3 for industrial (Cossipore) area, respectively. Winter concentrations of particulate pollutants were higher than other seasons, irrespective of the monitoring sites. It indicates a longer residence time of particulates in the atmosphere during winter due to low winds and low mixing height. Spread of air pollution sources and non-uniform mixing conditions in an urban area often result in spatial variation of pollutant concentrations. The higher particulate pollution at industrial area may be attributed due to resuspension of road dust, soil dust, automobile traffic and nearby industrial emissions. Particle size analysis result shows that PM10 is about 52% of TSP at residential area and 54% at industrial area.

Seasonal variations and chemical characterization of ambient PM 10 at residential and industrial sites of an urban region of Kolkata (Calcutta), India

Monitoring of ambient PM 10 (particulate matter which passes through a size selective impactor inlet with a 50% efficiency cut-off at 10 μm aerodynamic diameter) has been done at residential (Kasba) and industrial (Cossipore) sites of an urban region of Kolkata during November 2003 to November 2004. The measurements have been performed once a week during the study period. PM 10 mass concentrations ranged from 68.2 to 280.6 μg/m 3 at a residential site and 62.4 to 401.2 μg/m 3 at an industrial site. Metal constituents of ambient PM 10 deposited on quartz microfibre filter papers were identified using Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES). Chromium (Cr), zinc (Zn), lead (Pb), cadmium (Cd), nickel (Ni), manganese (Mn) and iron (Fe) are the seven toxic trace metals quantified from the measured PM 10 concentrations. Results identified zinc with maximum contribution of PM 10 among measured metals having concentrations of 0.49 μg/m 3 at the residential site, and 0.53 μg/m 3 at the industrial site. The PAH (polycyclic aromatic hydrocarbon) compounds namely, fluoranthene (Fl), pyrene (Py), benzo(a)anthracene (BaA), benzo(b)fluoranthene (BbF) and benzo(a)pyrene (BaP) have been analyzed using gas chromatography. The major PAH compound at the monitoring sites was BbF with 0.03 μg/m 3 at the residential site and 0.02 μg/m 3 at the industrial site. Total carbon (TC), inorganic carbon (IC) and organic carbon (OC) of PM 10 were analyzed using a carbon analyzer. Exposed quartz microfibre filter papers were also analyzed for water-soluble anions of fluoride (F −), chloride (Cl −), nitrate (NO 3 −), phosphate (PO 4 3−) and sulfate (SO 4 2−) using ion chromatography. Sulfate was found in maximum concentration among anionic species with a value of 1.2 μg/m 3 at the residential site, and 1.7 μg/m 3 at the industrial site. Meteorological parameters such as wind speed, wind direction, rainfall, temperature and relative humidity were collected simultaneously during the sampling period from the Indian Meteorological Department, Kolkata. A simultaneous meteorological study was performed to assess the influence of air masses by measured meteorological parameters. Winter concentrations of PM 10 and its chemical constituents were mainly higher than in other seasons, irrespective of the monitoring sites. It indicates a longer residence time of particulates in the atmosphere during winter due to low winds and low mixing height. Winter to monsoon ratio for PM 10 is 1.6 and 2.3 for residential and industrial sites, respectively. Summer to monsoon ratio of PM 10 observed in the study period was 1.3 for the residential site, and 1.4 for the industrial site. The higher particulate pollution in the industrial area may be attributed to resuspension of road dust, soil dust, automobile traffic and nearby industrial emissions. Spearman rank correlation coefficient analysis showed an inverse relationship between PM 10 and its chemical constituents with wind speed, temperature, rainfall and relative humidity.

A case study of the impact of Winter road sand/salt and street sweeping on road dust re-entrainment

Resuspended road dust is an important contributor to ambient particulate matter (PM). In areas with significant snow events, the use of wintertime roadway abrasives for traction control can result in increased PM emissions. An alternative control measure is to use chemical deicers prior to a snow event to minimize ice formation and reduce the need for abrasives. Street sweeping is also commonly used to reduce the impact of re-entrained abrasive material after the snow pack on the road has cleared. In this study, we performed roadside measurements of PM flux and instrumented vehicle PM measurements to evaluate the effectiveness of street sweeping to reduce dust re-entrainment and assess the impact of abrasives and deicers on ambient PM near an alpine lake (Lake Tahoe). The results indicate use of liquid deicers contributes less to road dust emissions than abrasives. Street sweeping was found to increase the PM 10 re-entrainment rate of the remaining road dust. Emission factors for roads in the study area (a snowy mountain climate) tend to decrease significantly from late Spring to early Summer by as much as a factor of 4.

Precision and repeatability of the TRAKER vehicle-based paved road dust emission measurement

Testing re-entrained aerosol kinetic emissions from roads (TRAKER), a vehicle based measurement system, has been reported as an alternative to silt measurements for estimating PM 10 paved road dust emissions. The precision of the TRAKER system was quantified with repeated measurements over the same roads. A prescribed driving route in Las Vegas, Nevada was traversed with the TRAKER on four consecutive days. The 154 km of paved roads were divided into 645 road segments each representing at least 20 data points and corresponding to links used in the county traffic demand and forecasting model. The TRAKER emission potential, which is related to the emission factor by a multiple of travel speed and provides a measure of a road segment's inherent PM 10 dust loading, was averaged over each road segment. Comparing the 4 days of sampling, the coefficient of variation (COV), the standard deviation divided by the average, was <10%, <20%, <50%, and <70% for 126, 402, 619, and 639 of the 645 road segments, respectively. The COV decreased with the speed at the time of measurement from 26% at 5–10 m s −1 to 14% at 25–30 m s −1. No discernible relationships were found between COV and number of data points per road segment, length of road segment, or direction of travel. Over the entire 154 km route, emission potentials on the 4th day were slightly lower than the prior 3 days, owing either to actual changes in road conditions or bias introduced into the measurement by surface wind speed which was highest on the 4th day.

Fresh Gasoline Emissions, Not Paved Road Dust, Alter Cardiac Repolarization in ApoE&lt;sup&gt;−/−&lt;/sup&gt; Mice

Fresh vehicular emissions potentially represent a ubiquitous environmental concern for cardiovascular health. We compared electrocardiographic effects of fresh gasoline engine emissions with resuspended paved road dust in a mouse model of coronary insufficiency. Apolipoprotein E (ApoE)-/- mice on a high fat diet were exposed by whole-body inhalation to either gasoline emissions at 60 microg/m3 particulate matter (PM), an equivalent atmosphere with particles filtered out of the whole exhaust, or paved road dust at 0.5 and 3.5 mg /m3 for 6 h/d for 3 d. Radiotelemetry recordings of electrocardiogram (ECG) were analyzed for changes in T-wave morphology (QT interval, T-wave amplitude, and T-wave Area). Following exposures, lung lavage and blood samples were obtained to assay for markers of pulmonary and systemic inflammation. No exposure induced significant changes in heart rate and only the high concentration of road dust induced signs of pulmonary inflammation. T-wave area exhibited significant deviation from baseline values during exposure to gasoline exhaust particulates, but not to either concentration of road dust or gasoline emissions sans particulates. Gasoline-exposed mice demonstrated elevated plasma endothelin-1, but did not cause systemic inflammation. These data support the hypothesis that freshly-generated engine emissions, as opposed to resuspended paved road dust, may drive cardiac effects that have been observed at road-sides in the environment. The absence of ECG effects for both very high concentrations of road dust PM and equivalent concentrations of the vapor/gas phase of gasoline engine exhaust further indicate the specific risk conferred by fresh vehicular PM.

Fine (PM2.5) and Coarse (PM2.5-10) Particulate Matter on A Heavily Trafficked London Highway: Sources and Processes

A large dataset for PM2.5 and PMcoarse (PM2.5-10) concentrations monitored near a busy London highway (Marylebone Road) has been analyzed to define the factors that lead to high concentrations. The following have been highlighted as major influencing parameters: wind speed, prevailing wind direction (because of its role on the microscale dispersion within the street), the daily cycle of the atmospheric boundary layer (stable during the night/ convective and mixed during the day), and traffic density. The mainly diesel heavy-duty vehicles are the main source of fine particulate matter at Marylebone Road. In particular, lorries (trucks) dominate PM10 exhaust emissions which are mainly in the fine (<2.5 microm) size range. A strong correlation with PMcoarse suggests that the heavy-duty traffic is largely responsible for this component also. Substantial local increments in PM2.5 and PMcoarse due to traffic have been estimated and a large part of the increment in PMcoarse concentrations is inferred to arise from resuspended road dust emissions since the contribution of abrasion processes estimated from emission factors is modest. Despite the strong influence of traffic on PM concentrations measured at Marylebone Road the analysis of factors leading to the highest 5% of hourly concentrations of PM10 at Marylebone Road reveals that almost half of these events were due to building works. The other events occurred when all or most of the key factors occurred simultaneously (heavy traffic, poor dispersion, etc.). Some episodes of high PM2.5 concentrations were associated with long-range transport in which the regional PM2.5 constituted most of the local concentrations.

Effect of vehicle characteristics on unpaved road dust emissions

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×(km h−1) for a light (∼1200 kg) passenger car to EF=48×(km h−1) for large military vehicles (∼18 000 kg). In comparison to emission estimates derived using US EPA AP-42 methods the measured emission factors indicate larger than estimated contributions for speeds generally>10–20 km h−1 and for vehicle weights>3000 kg. 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.

Tailpipe, resuspended road dust, and brake-wear emission factors from on-road vehicles

Intensive mass and chemical measurements were performed at roadside locations in Reno, Nevada, and Durham/ Research Triangle Park), North Carolina to derive tailpipe, resuspended road dust, and brake-wear emission factors from in-use vehicles. Continuous particulate matter (PM) data were utilized to derive total emission factors while integrated PM data were used to attribute the calculated emission factors to different mechanisms using chemical mass balance receptor modeling and scanning electron microscopy techniques. Resuspended road dust and tailpipe emissions were found to be the dominant mechanisms that contribute significantly to the total PM10 and PM2.5 emission factors, respectively. Small contributions from brake-wear were observed at locations where strong braking occurs, but no tirewear was seen at any sampling location. PM10 emission rates from light-duty sparkignition (LDSI) vehicles ranged from 40 to 780 mg/km, 10 to 70 mg/km, and 0 to 80 mg/km per vehicle for road dust, tailpipe, and brake-wear, respectively. PM10 emission rates from heavy-duty vehicles ranged from 230 to 7800 mg/km, 60 to 570 mg/km, and 0 to 610 mg/km per vehicle for road dust, tailpipe, and brake-wear, respectively. PM2.5 emission rates from LDSI vehicles ranged from 2 to 25 mg/km, 10 to 50 mg/km, and 0 to 5 mg/km per vehicle for road dust, tailpipe, and brake-wear, respectively. PM2.5 emission rates from heavy-duty vehicles ranged from 15 to 300 mg/km, 60 to 480 mg/km, and 0 to 15 mg/km per vehicle for road dust, tailpipe, and brake-wear, respectively. r 2003 Elsevier Ltd. All rights reserved.

Vehicle-based road dust emission measurement: I—methods and calibration

Abstract Testing re-entrained aerosol kinetic emissions from roads (TRAKER) is a vehicle-based method for measuring road dust emissions. Particulate matter is sampled in front and behind a vehicle's tire and the difference in PM concentration is related to emissions. This paper describes the most recent developments of TRAKER. The loss of particles within the inlet lines, the response of the TRAKER signal (differential PM concentration) to vehicle speed, and the relationship between the TRAKER signal and unpaved road dust PM 10 emissions were examined. Losses of particles to the walls in the inlet lines were similar for the left and right inlets and were less than the inter-instrument precision for particles between 0.56 and 7.3 μm in diameter. When summed over the PM 10 size range, losses were less than 20%. Line losses were also characterized when a dilution system was used to sample emissions from unpaved roads. Two independent tests indicated that the TRAKER signal increases as the cube of the speed for a given road dust loading. Simultaneous measurement of PM 10 dust emitted behind the tires by TRAKER with PM 10 flux measured using upwind/downwind towers suggested that the emission factor for road dust was proportional to the cube root of the TRAKER signal. The results also showed a linear relationship between unpaved road dust PM 10 emissions and vehicle speed.

Vehicle-based road dust emission measurement—Part II: Effect of precipitation, wintertime road sanding, and street sweepers on inferred PM10 emission potentials from paved and unpaved roads

Abstract Testing Re-Entrained Kinetic Emissions from Roads (TRAKER) is a new technique to infer paved and unpaved road dust PM 10 emission potentials based on particulate matter (PM) measurements made onboard a moving vehicle. Light scattering instruments mounted in front and behind the vehicle's tires measure the differential particle concentration of dust suspended by the vehicle's tire in contact with the road surface. Through empirical regressions relating the differential concentration (i.e. TRAKER signal) with the vehicle speed and the downwind flux of PM 10 particles from the road, an equation is derived to infer the speed independent road dust emission potential from the measured TRAKER signal. Measurements from TRAKER offer a new perspective on the processes that affect road dust emissions. The system was used to investigate temporal changes in emission potentials from paved roads in both the winter and summer in the Treasure Valley in Southwest Idaho. During the 3-week wintertime sampling period, the residential road dust PM 10 emission potential decreased by ∼50%. Summertime PM 10 emission potentials were similar to those observed at the end of the winter sampling and showed no upward or downward trends. Wintertime unpaved road emissions increased consistently with the number of days since the last rainfall. Measurement of road dust emission potentials after road sanding on dry roads indicated a 75% increase in PM 10 emissions after 2.5 h. This effect was short lived and emission potentials returned to their pre-sanding levels within 8 h of the sand application. Street sweeping with mechanical and vacuum sweepers was found to offer no measurable reduction in PM 10 emission potentials. On several roads, the PM 10 emission potentials actually increased immediately after vacuum sweeping. Long term effects of street sweeping on road dust emissions were not evaluated as part of this study and may offer some overall reduction in PM emissions from paved roads.

Vehicle-based road dust emission measurement (III): effect of speed, traffic volume, location, and season on PM10 road dust emissions in the Treasure Valley, ID

Abstract The testing re-entrained aerosol kinetic emissions from roads (TRAKER) road dust measurement system was used to survey more than 400 km of paved roads in southwestern Idaho during 3-week sampling campaigns in winter and summer, 2001. Each data point, consisting of a 1-s measurement of particle light scattering sampled behind the front tire, was associated with a link (section of road) in the traffic demand model network for the Treasure Valley, ID. Each link was in turn associated with a number of characteristics including posted speed limit, vehicle kilometers traveled (vkt), road class (local/residential, collector, arterial, and interstate), county, and land use (urban vs. rural). Overall, the TRAKER-based emission factors based on location, setting, season, and speed spanned a narrow range from 3.6 to 8.0 g/vkt. Emission factors were higher in winter compared to summer, higher in urban areas compared to rural, and lower for roads with fast travel speeds compared to slower roads. The inherent covariance between traffic volume and traffic speed obscured the assessment of the effect of traffic volume on emission potentials. Distance-based emission factors expressed in grams per kilometer traveled (g/vkt) for roads with low travel speeds (∼11 m/s residential roads) compared to those with high travel speeds (∼25 m/s interstates) were higher (5.2 vs. 3.0 g/vkt in summer and 5.9 vs. 4.9 g/vkt in winter). However, emission potentials which characterize the amount of suspendable material on a road were substantially higher on roads with low travel speeds (0.71 vs. 0.13 g/vkt/(m/s) in summer and 0.78 vs. 0.21 g/vkt/(m/s) in winter). This suggested that while high speed roads are much cleaner (factor of 5.4 in summer), on a vehicle kilometer traveled basis, emissions from high and low speed roads are of the same order. Emission inventories based on the TRAKER method, silt loadings obtained during the field study, and US EPA's AP-42 default values of silt loading were compared. PM 10 paved road dust emission inventories calculated with the TRAKER method were 61% higher in winter and 180% higher in summer than inventories calculated from on-site silt loading measurements. Emissions calculated from silt loading measurements conducted on-site indicated that the AP-42 default values are too low for the Treasure Valley by a factor of 1.5 for summer conditions and by a factor of 3.8 for winter. Both silt loading and TRAKER are techniques that were calibrated against the horizontal flux of dust, which was estimated by the difference in PM 10 concentration between instruments located upwind and downwind of an unpaved road. The upwind/downwind method, and therefore both silt loading and TRAKER, gives a measure of the dust emitted near the source, and not the dust that can be transported on a regional or air shed scale. Correcting the measured dust emissions for deposition and removal near the source is outside the scope of this work, but is a continuing area of research among dispersion modelers.

Source apportionment of secondary airborne particulate matter in a polluted atmosphere.

Secondary airborne particulate matter formed from gas-phase pollutants contributes significantly to the most severe particulate air quality events that occur in the United States each year. In this study, a mechanistic air quality model is demonstrated that can predict source contributions to the size distribution of secondary airborne particulate matter. Calculations performed for a typical air quality episode in Southern California show that NOx released from diesel engines and catalyst-equipped gasoline engines account for the majority of the secondary particulate nitrate aerosol measured at inland locations. NH3 released from catalyst-equipped gasoline engines, farm animals, and residential sources account for the majority of the secondary particulate ammonium ion at inland locations in the region. When both tailpipe and road dust emissions are considered, transportation sources dominate the size distribution of total (primary plus secondary) airborne particulate matter in the South Coast Air Basin during the episode studied. These findings suggest that the public health risk associated with air pollution released from transportation sources is significant relative to other public health threats such as traffic accidents.

Evaluation of hexahydrated magnesium chloride (Bischofite) performance as a chemical stabilizer of granular road surfaces

Hexahydrated Magnesium Chloride or Bischofite is a salt. It has different properties that enable it to be useful as a chemical stabilizer of granular road surfaces: its capacity of absorbing and retaining humidity from its surrounding environment, increases water surface tension and decreases its vapor pressure. The objective of this research was to evaluate Bischofite performance as a chemical stabilizer of granular road surfaces. Research was based on laboratory tests and the evaluation of test road sections of granular road surfaces stabilized with Bischofite in arid and semi-arid zones of Chile. In general, the field trial results have been more conclusive than the laboratory tests. The use of Bischofite creates a stable granular road surface, reduces potholes, corrugations, erosion and dust emissions, and improves the riding quality.

Measurement of emission factor of road dust in a wind tunnel

One of the critical problems in making an effective strategy to control road dust emission is to estimate the emission factor accurately. A wind tunnel was built in the laboratory to measure the emission factor of road dust under different wind acceleration conditions. Test road dusts were collected from two sites, one from the construction site where a DRAM factory was being constructed in the Science Industrial Park of Hsin-Chu (dust sample #1) and the other from an unpaved road at Nan Laio area of Hsin-Chu (dust sample #2). The dust samples were first sieved using a standard No. 325 mesh to remove particles greater than 44 μm. Thereafter, the dust samples were dried and then contained within an aluminum cell of 5 (width)×5 (length)×0.2 cm (depth), which was embedded in a working platform in the wind tunnel. The surface of dust samples was kept flush with the plate before testing. Test results show that the air acceleration rate affects the emission factor significantly. As the air acceleration rate is increased from 0.1 to 1.5 m/s2, the emission factor is increased linearly from 1.0 to 7.0×10−4 kg/m2-s for sample #1, and from 0.1 to 1.0×10−4 kg/m2-s for sample #2.Test results show that the air acceleration rate has no significant effect on the threshold wind speed for reentrainment, which was found to be 10–12 m/s for sample #1, and 9–10 m/s for sample #2. While the edge effect at the surface of the dust sample has no significant effect on the threshold wind speed for reentrainment, it increases both reentrained dust concentration and emission factor significantly.

Testing Re-entrained Aerosol Kinetic Emissions from Roads : a new approach to infer silt loading on roadways

PM 10 and PM 2.5 emissions from roadways are currently estimated using the silt loading on the road surface as a surrogate for the emissions potential of road dust. While the United States Environmental Protection Agency prescribes this method in AP-42, there is considerable cost associated with silt loading measurements; it is feasible to sample only a small portion of a roadway network. A new approach for measuring the concentration of suspendable PM 10 above road surfaces has been developed to obtain a more spatially representative estimate of a road's potential to emit dust. The Testing Re-entrained Aerosols Kinetic Emissions from Roads (TRAKER) system uses real-time aerosol sensors mounted on a vehicle to measure the concentration of dust suspended from the road while the vehicle is in motion. When coupled with a Global Positioning System (GPS) instrument, TRAKER can be used to efficiently survey the changes in suspendable particles due to varying road conditions over a large spatial domain. In a recent study on paved roads in Las Vegas, the TRAKER system was compared with collocated silt loading measurements. The TRAKER system was also used to survey the relative amounts of suspendable road dust on approximately 300 miles of paved roads. The system provides a unique perspective on road dust sources and their spatial distribution. Results of this study indicated that the difference of the PM 10 concentrations measured behind the tire and on the hood is exponentially related to vehicle speed. This was an interesting finding because current AP-42 road dust emissions estimation methods do not include vehicle speed as a factor in the emissions calculations. The experiment also demonstrated that the distribution of suspendable material on roadways is highly variable and that a large number of samples are needed to represent road dust emissions potential on an urban scale for a variety of road and activity conditions.

Allergens in Paved Road Dust and Airborne Particles

Paved road dust present on the surface of streets in Southern California consists of a complex mixture of soil dust, deposited motor vehicle exhaust particles, tire dust, brake lining wear dust, plant fragments, and other biological materials. The research presented here shows that allergens from at least 20 different source materials are found in the paved road dust. These include pollens and pollen fragments, animal dander, and molds. When paved road dust is resuspended into the atmosphere by passing vehicle traffic, allergen concentrations in the air are increased above the levels that would prevail without the vehicle traffic. Using immunological assays that measure the proteins extracted from environmental samples that bind to IgE antibodies present in the blood serum of allergenic patients, it is possible to measure the allergen concentrations present in paved road dust and in airborne particle samples. Total protein contributions to monthly average airborne TSP and PM_(10) concentrations are found to be in the range from 1 to 5.8 μg m^(-3), potentially accounting for a significant fraction of the airborne particulate organic material that has not been identified to date by GC/MS techniques. Results show that up to 5−12% of the allergenicity of atmospheric total suspended particulate matter samples at Long Beach and Rubidoux, CA, is attributable to paved road dust emissions. In an industrial area of urban central Los Angeles where there is less proximity to vegetation and domestic activities, the paved road dust contribution to airborne allergen concentrations is lower, accounting for approximately 0.5% of the total allergenic activity of the atmospheric particle samples. In conclusion, paved road dust when entrained into the atmosphere by passing traffic is a source of allergen exposure for the general population and could be more important in areas with more abundant vegetation or with closer proximity of populations to major highways than is the case for the Southern California air monitoring sites studied here.

Urban air pollution source apportionment using a combination of aerosol and gas monitoring techniques

The dominating local and regional sources of gaseous and particulate air pollution in the city of Lund (69,000 inhabitants) in southern Sweden were characterized using a combination of aerosol and gas-phase monitoring techniques. Twelve-hour samples were taken at two stations of both fine and coarse fraction urban aerosols with a stacked filter unit during the four-week measurement campaign in March/April 1993. The aerosol samples were analysed with PIXE for 14 major and trace elements. In addition, gaseous species (SO 2, NO 2, O 3) were measured simultaneously with the DOAS technique over two stretches, crossing each other only 300 m from the downtown aerosol sampling site. The combined results obtained by the analytical techniques PIXE and DOAS for aerosol and gas measurements, respectively, were used in an absolute receptor model in order to identify the major sources affecting the measurement sites and to apportion the measured air pollutants to the identified sources. The gases (SO 2, NO 2, O 3) could also be attributed to specific sources by combining the trace elemental concentration data for the fine fraction aerosol with that of the gaseous species in the receptor model. According to the absolute principal component analysis (APCA) model, the dominant sources for the measured species were resuspended road dust, automobile and diesel emissions, combustion of oil and coal, ferrous and non-ferrous smelters and sea spray. Of these, the sources related to traffic are mainly local in character while the others constitute a regional background. For a small city in southern Scandinavia like Lund with only light industry, the long-range transported air pollutants make up a significant part of the fine fraction aerosol.

Optical examination of a mesophase coal tar pitch

Particulate matter (PM) is an important constituent of atmospheric pollution especially in areas under the influence of industrial emissions. Megalopolis is a small city of 10,000 inhabitants located in central Peloponnese in close proximity to three coal opencast mines and two lignite fired power plants. 50 PM10 samples were collected in Megalopolis during the years 2009–11 for elemental and multivariate analysis. For the elemental analysis PIXE was used as one of the most effective techniques in APM analytical characterization. Altogether, the concentrations of 22 elements (Z = 11–33), whereas Black Carbon was also determined for each sample using a reflectometer. Factorization software was used (EPA PMF 3.0) for source apportionment analysis. The analysis revealed that major emission sources were soil dust 33% (7.94 ± 0.27 μg/m3), biomass burning 19% (4.43 ± 0.27 μg/m3), road dust 15% (3.63 ± 0.37 μg/m3), power plant emissions 13% (3.01 ± 0.44 μg/m3), traffic 12% (2.82 ± 0.37 μg/m3), and sea spray 8% (1.99 ± 0.41 μg/m3). Wind trajectories have suggested that metals associated with emission from the power plants came mainly from west and were connected with the locations of the lignite mines located in this area. Soil resuspension, road dust and power plant emissions increased during the warm season of the year, while traffic/secondary, sea spray and biomass burning become dominant during the cold season.

Road dust emission inventory for the metropolitan area of Shanghai City

An inventory of dust emission from paved roads of the metropolitan area of Shanghai City is accomplished on the basis of field experiments and an inventory of traffic and road conditions. The result shows the annual amount of road dust emission contributed to the ambient TSP pollution of Shanghai City is approximately 12,300 tonnes (in 354 km 2).