Roadside measurements of particulate matter size distribution (original) (raw)
Related papers
Atmospheric Environment, 2004
The spatial variability of aerosol number and mass along roads was determined in different regions (urban, rural and coastal-marine) of the Netherlands. A condensation particle counter (CPC) and an optical aerosol spectrometer (LAS-X) were installed in a van along with a global positioning system (GPS). Concentrations were measured with high-time resolutions while driving allowing investigations not possible with stationary equipment. In particular, this approach proves to be useful to identify those locations where numbers and mass attain high levels ('hot spots'). In general, concentrations of number and mass of particulate matter increase along with the degree of urbanisation, with number concentration being the more sensitive indicator. The lowest particle numbers and PM 1 -concentrations are encountered in a coastal and rural area: o5000 cm À3 and 6 mg m À3 , respectively. The presence of sea-salt material along the North-Sea coast enhances PM >1 -concentrations compared to inland levels. High-particle numbers are encountered on motorways correlating with traffic intensity; the largest average number concentration is measured on the ring motorway around Amsterdam: about 160 000 cm À3 (traffic intensity 100 000 veh day À1 ). Peak values occur in tunnels where numbers exceed 10 6 cm À3 . Enhanced PM 1 levels (i.e. larger than 9 mg m À3 ) exist on motorways, major traffic roads and in tunnels. The concentrations of PM >1 appear rather uniformly distributed (below 6 mg m À3 for most observations). On the urban scale, (large) spatial variations in concentration can be explained by varying intensities of traffic and driving patterns. The highest particle numbers are measured while being in traffic congestions or when behind a heavy diesel-driven vehicle (up to 600 Â 10 3 cm À3 ). Relatively high numbers are observed during the passages of crossings and, at a decreasing rate, on main roads with much traffic, quiet streets and residential areas with limited traffic. The number concentration exhibits a larger variability than mass: the mass concentration on city roads with much traffic is 12% higher than in a residential area at the edge of the same city while the number of particles changes by a factor of two (due to the presence of the ultrafine particles (aerodynamic diameter o100 nm). It is further indicated that people residing at some 100 m downwind a major traffic source are exposed to (still) 40% more particles than those living in the urban background areas. r
Atmospheric Environment, 2005
On-road size-resolved particulate emission factors were computed using concurrently measured carbon monoxide (CO) as a freeway dilution indicator and correlating roadside particle measurements to CO measurements. The emission factors derived for the total particle number agree well with previous on-road investigations. However, this study extends this analysis to produce unique receptor-dependent, size-resolved, road and grid-level emission factor distributions. Both mileage-and fuel-based particle number and mass emission factors at road and grid levels, along with CO emission factors, are presented and the results from freeways with distinctly different percentages of heavyduty diesel truck traffic are compared. The effects of plume processing on particle number near roadways are shown to be much more profound than on particle mass, further indicting that the adverse health effects observed near roadways are at least partially related to particle numbers. r
A Quantitative Description of Vehicle Exhaust Particle Size Distributions in a Highway Tunnel
Journal of the Air & Waste Management Association, 2004
During the period May 18-May 22, 1999, a comprehensive study was conducted in the Tuscarora Mountain Tunnel on the Pennsylvania Turnpike to measure real-world motor-vehicle emissions. As part of this study, size distributions of particle emissions were determined using a scanning mobility particle sizer. Each measured size distribution consisted of two modes: a nucleation mode with midpoint diameter less than 20 nm and an accumulation mode with midpoint diameter less than 100 nm. The nucleation and accumulation components in some distributions also exhibited second maxima, which implies that such particle size distributions are superpositions of two particle size distributions. This hypothesis was utilized in fitting the particle size distributions that exhibited second maxima with four lognormal distributions, two for the nucleation mode and two for the accumulation mode. The fitting assumed that the observed particle size distribution was a combination of two bimodal lognormal distributions, one attributed to the heavy-duty diesel (HDD) vehicles and another attributed either to a different class of HDD vehicles or to the light-duty spark ignition vehicles. Based on this method, estimated particle production rates were 1.8 ϫ 10 13 and 2.8 ϫ 10 14 particles/vehicle-km for light-duty spark ignition and HDD vehicles, respectively, which agreed with independently obtained estimates.
Measurements of mobile source particulate emissions in a highway tunnel
International Journal of Vehicle Design, 2001
Recent studies have linked atmospheric fine particulate matter (PM 2.5) with human health effects. In many urban areas, mobile sources are the dominant source of PM 2.5. Dynamometer studies have also implicated diesel engines as being a significant source of ultrafine particles. In order to characterise particulate emissions from in-use vehicles, we performed an onroad study of emissions from vehicles operating in the Tuscarora Mountain Tunnel along the Pennsylvania Turnpike. As part of this study we obtained chemically speciated, size-segregated PM emission rates, particle size distributions, chemically speciated profiles of diesel emissions for use in source apportionment studies, a comparison with years past how much improvement there has actually been in diesel particulate emission rates, and measurements of particulate emission rates from light-duty gasoline vehicles to evaluate the relative significance of this source. This paper describes the experimental methods and presents the preliminary results of the on-road particulate emissions measurements.
Size-segregated particulate matter and gaseous emissions from motor vehicles in a road tunnel
Atmospheric Research, 2015
In order to address road traffic emissions, studies need to be performed under realistic driving conditions where the input from other sources is minimised. Measurements in traffic tunnels have been used for quantifying emissions, but so far no study has established emission factors (EFs) for Southern Europe. To fill this gap, a sampling campaign was carried out for one week in the Liberdade Avenue tunnel (Braga, Portugal). The campaign included the monitoring of gaseous pollutants (CO 2 , CO, NO x) and suspended particulate matter (PM) at two sites, one in the tunnel and another in an urban background location. Organic and elemental carbon (OC and EC) in sizesegregated particles (PM 0.5, PM 0.5-1 , PM 1-2.5 and PM 2.5-10) were determined by a thermal-optical system, whereas major and trace elements were analysed by ICP-MS and ICP-AES. PM 0.5 accounted for 56% of the PM 10 mass, while PM 2.5-10 represented only 12%. The carbonaceous fraction was concentrated in PM 0.5 , encompassing 88% of the EC and 67% of the OC present in PM 10. Elements attributable to non-exhaust emissions could be divided into two groups. Fe, Ba, Cu, Sb, Sn and Zn, from tyre and brake wear, were more abundant in particles between 1 and 2 μm. Ca, Al, K, Sr and Ti, associated with soil resuspension, were mainly present in particles N 2 μm. The average EFs of CO, CO 2 and NO x were 212, 4.02 and 1.22 g veh −1 km −1 , respectively, while values of 152 mg PM 10 veh −1 km −1 and 133 mg PM 2.5 veh −1 km −1 were obtained for the particles. OC and EC emission factor was 39 mg veh −1 km −1 for PM 10. The corresponding OC and EC values for PM 2.5 were 34 and 38 mg veh −1 km −1. The EFs are slightly lower than those found for other tunnels, but within the ranges presented by the EMEP/EEA inventory.
Atmospheric Environment, 2006
Atmospheric particulate matter (PM) presence at four urban sites in the city of Milan (Italy) is characterised in terms of particle size distribution (number, surface, volume) for the cold and warm season. Simultaneous monitoring of particle number concentration (from 300 nm up to 20 mm of diameter) has been performed between August 2002 and December 2004 by means of a low-volume particle size laser analyser. The monitoring sites are characterised by a different exposure to traffic emissions, enabling for the assessment of the role of this source on both PM concentration levels and on particle size distributions. Data from an urban background site, not directly exposed to traffic emission, a site in a residential area of the city, and two kerbside sites (one at open air, one in a road tunnel) directly exposed to the traffic emissions are compared. Weekdays' and weekends' data from the urban background site are analysed for assessing the effect of the reduced traffic circulation on Sundays.
Atmospheric Research, 2016
Particulate matter samples were collected in a road tunnel in Lisbon (PM 0.5 , PM 0.5-1 , PM 1-2.5 , and PM 2.5-10 ) and at two urban locations representing roadside and background stations (PM 2.5 and PM 2.5-10 ). Samples were analysed for organic and elemental carbon (OC and EC), n-alkanes, n-alkenes, hopanes, some isoprenoid compounds, and steranes. Particulate matter concentrations in the tunnel were 17-31 times higher than at roadside in the vicinity, evidencing an aerosol origin almost exclusively in fresh vehicle emissions. PM 0.5 in the tunnel comprised more than 60% and 80% of the total OC and EC mass in PM 10 , respectively. Concentrations of the different aliphatic groups of compounds in the tunnel were up to 89 times higher than at roadside and 143 times higher than at urban background. Based on the application of hopane-to-OC or hopanes-to-EC ratios obtained in the tunnel, it was found that vehicle emissions are the dominant contributor to carbonaceous particles in the city but do not represent the only source of these triterpenic compounds. Contrary to what has been observed in other studies, the Σhopane-to-EC ratios were higher in summer than in winter, suggesting that other factors (e.g. biomass burning, dust resuspension, and different fuels/engine technologies) prevail in relation to the photochemical decay of triterpenoid hydrocarbons from vehicle exhaust.
A Study on Particulate Matter From an Area With High Traffic Intensity
The research is focusing on analyzing the concentrations of particulate matter (PM) next to a highly congested road section, with 39,900 as a maximum number of vehicles per 24 h, in the vicinity of Timisoara, Romania. Concentrations have been measured in multiple episodes using two different measurement methods, gravimetric and dynamic light scattering, showing a disperse range of PM concentrations. Presence of metal particles in the samples have been analyzed using an electron microscope. Additionally, impact on human health is described by evaluating results for inhalable, thoracic, and alveolar sized particles.
Atmospheric Chemistry and Physics Discussions, 2013
The notable increase in biofuel usage by the road transportation sector in Brazil during recent years has significantly altered the vehicular fuel composition. Consequently, many uncertainties are currently found in particulate matter vehicular emission profiles. In an effort to better characterise the emitted particulate matter, measurements of aerosol physical and chemical properties were undertaken inside two tunnels located in the São Paulo Metropolitan Area (SPMA). The tunnels show very distinct fleet profiles: in the Jânio Quadros (JQ) tunnel, the vast majority of the circulating fleet are light duty vehicles (LDVs), fuelled on average with the same amount of ethanol as gasoline. In the Rodoanel (RA) tunnel, the particulate emission is dominated by heavy duty vehicles (HDVs) fuelled with diesel (5 % biodiesel). In the JQ tunnel, PM 2.5 concentration was on average 52 µg m −3 , with the largest contribution of organic mass (OM, 42 %), followed by elemental carbon (EC, 17 %) and crustal elements (13 %). Sulphate accounted for 7 % of PM 2.5 and the sum of other trace elements was 10 %. In the RA tunnel, PM 2.5 was on average 233 µg m −3 , mostly composed of EC (52 %) and OM (39 %). Sulphate, crustal and the trace elements showed a minor contribution with 5 %, 1 %, and 1 %, respectively. The average OC : EC ratio in the JQ tunnel was 1.59 ± 0.09, indicating an important contribution of EC despite the high ethanol fraction in the fuel composition. In the RA tunnel, the OC : EC ratio was 0.49 ± 0.12, consistent with previous measurements of diesel-fuelled HDVs. Besides bulk car-bonaceous aerosol measurement, polycyclic aromatic hydrocarbons (PAHs) were quantified. The sum of the PAHs concentration was 56 ± 5 ng m −3 and 45 ± 9 ng m −3 in the RA and JQ tunnel, respectively. In the JQ tunnel, benzo(a)pyrene (BaP) ranged from 0.9 to 6.7 ng m −3 (0.02-0. 1 ‰ of PM 2.5 ) whereas in the RA tunnel BaP ranged from 0.9 to 4.9 ng m −3 (0.004-0. 02 ‰ of PM 2.5 ), indicating an important relative contribution of LDVs emission to atmospheric BaP.
Primary particle formation from vehicle emissions during exhaust dilution in the roadside atmosphere
Atmospheric Environment, 2003
Measurements of particle number size distribution in the range 11-452 nm have been made on the side of the busy Marylebone Road in central London over a period from April 1998 to August 2001. The data have been analysed to demonstrate the influences of meteorological factors upon different size fractions and upon the overall size distribution. The relationship to traffic volumes indicates that the accumulation mode particles are associated with emissions from heavy-duty traffic (mainly diesel vehicles) whilst particles in the range 30-60 nm show a stronger association with lightduty traffic. Both of these size fractions show the anticipated dilution effect with increasing wind speed. Particles in the 11-30 nm range behave anomalously showing no clear relationships to traffic volumes and a lesser effect of dilution by increasing wind speed than for the larger particles. Particles in this fraction tend to peak in the early morning showing an inverse association with air temperature. It is concluded that this size range contains freshly nucleated particles formed as the exhaust gases are diluted with ambient air. r