Variations In Particulate Matter Concentrations Research Articles

Mobile measurements and regression modeling of the spatial particulate matter variability in an urban area

During 5 different periods between summer 2009 and spring 2011, mobile measurements were carried out in the city of Aachen, Germany, in order to capture the spatial variability of particulate matter concentrations in urban and suburban environments. Results show a large spatial variability on a scale of tens of meters, mainly depending on traffic density and building structure. Spatial coefficients of variation exhibit larger spatial variability for PM10 than for PM2.5 and larger variability in traffic influenced inner city environments than in suburban areas. Based on the results of an extensive campaign, a regression model is developed for the prediction of PM10 and PM2.5 distributions over the city area. The three predictors for the regression model are an exponential PM concentration profile simulated on the basis of PM10 and PM2.5 traffic emissions, building density and green area density within radii of 50m and 100m. The model shows good agreement between measured and modeled PM levels during the campaign used for the model training with R2 values of 0.79 and 0.65, RMSE of 1.9μg/m3 and 1μg/m3 for PM10 and PM2.5, respectively. The model is further validated using data from the remaining measurement campaigns and modeling of PM levels at monitoring sites that were not used for the training of the regression model. For the total number of 59 monitoring sites, the regression model shows R2 values of 0.77 (PM10) and 0.61 (PM2.5) with RMSE of 2.3μg/m3 and 1.2μg/m3. The modeled concentrations are generally in better accordance with measured concentrations for PM10 than for PM2.5 concentrations. We attribute this to higher spatial homogeneity of PM2.5 levels compared to coarse particles. Inner city PM levels at traffic influenced sites are better reproduced by the model than suburban concentrations which exhibit the smallest spatial variability.

Analysis of Data From Ambient PM<SUB>10</SUB> Concentration Monitoring in Volos in the Period 2005-2010

This paper presents the results of a monitoring campaign for ambient PM10 concentrations in Volos, Greece in the period 2005-2010. The aim is to give an overview of the evolution of particulate pollution, discuss effects of the micro-climate and demonstrate that PM10 monitoring may be carried out with low-cost measurement instruments at a community level. Statistical processing of the 2009-2010 measurement data indicates a negative correlation of PM10 with ambient air temperature and a positive correlation with relative humidity. Low PM10 concentrations are associated with E to SE winds and high concentrations with NW to N winds. Daily variation of particulate matter concentrations follows well established patterns with peaks at 09:00-10:00 and 23:00-24:00. The operation of an expanded PM10 monitoring network is under way.

Small scale particulate matter measurements and dispersion modelling in the inner city of Liège, Belgium

In the framework of the Interreg-IV ‘PM-Lab’ project a local-scale exercise was set up to evaluate air pollution in terms of particulate matter (PM) within the centre of Liège, Belgium (pop. 190,000). Sixteen sites distributed on a boulevard and its side streets were selected to determine the spatio-temporal variation of PM concentration in this traffic-dominated area. In addition to the in situ measurements numerical simulations were performed by means of AUSTAL2000. The performance of this Lagrangian dispersion model was checked through some basic qualitative and quantitative comparisons. As the model was able to detect highest PM concentrations both in space and time, test scenarios of emission reductions were also run in order to examine the impact of different traffic related measures.

Variations of Particulate Matter Concentrations and Particle-Associated Substances in Latvia

Variations of Particulate Matter Concentrations and Particle-Associated Substances in Latvia

Size Distribution and Source Identification of Airborne Particulate Matter and Metallic Elements in a Typical Industrial City

The size distribution of airborne particulate matter (PM) and the concentrations of associated metallic elements were investigated in a busy urban region of a typical Korean industrial city. The PM concentrations measured during the spring, except for those in the size range of 1.1 to 2.1 <TEX>${\mu}m$</TEX>, were slightly higher than the PM concentrations in the summer. Coarse particles contributed greatly to the variation in PM concentrations in the spring, while fine and submicron particles contributed largely to the variation in PM concentrations in the summer. The difference in size modes of the PM concentrations between spring and summer may be explained by the Asian dust effect and its accompanying wind direction and speed. Extremely high enrichment factors (EFs) values (6,971 to 60,966) for all of the size distributions in PM were identified for cadmium (Cd). High EFs values (12 to 907) were also identified for other heavy metals including Cr, Cu, Ni, Pb, Zn and Mn. Low EF values (0.29 to 8.61) were identified for Ca, K, Mg and Na. These results support the common hypothesis that most heavy metals in ambient PM have anthropogenic sources and most light metals have crustal sources. The results of principal components analyses and cluster analyses for heavy metals indicate that the principal sources of PM and metals were emissions from non-ferrous metal smelters, oil combustion, incinerators, vehicular traffic and road dust.

Spatial variability of particulates in homes: Implications for infant exposure

Personal monitoring of particulate matter (PM) exposure in infants is difficult. Indirect, microenvironment modelling methods are more practical. Infants spend most of their time indoors at home and the aim of this study was to investigate spatial variations in PM concentrations within homes. Three size fractions of PM - particles with an aerodynamic diameter of less than 10 microm (PM(10)), less than 2.5 microm (PM(2.5)) and total suspended particulates (TSP) - were monitored in the homes of 77 infants (0-2 years) using a multi-stage virtual impactor. In all homes PM was monitored simultaneously in the main living room at heights of 1.4 m and 0.2 m from the floor. In 26 of these homes monitoring was also conducted simultaneously in the infant's bedroom. Further, PM(10) was measured simultaneously in the living room, bedroom and child's cot in 14 homes using a real-time photometer. All homes in the study were non-smoking households. On average, there were no significant differences between concentrations of any of the different PM size fractions measured at the two heights (living room) and between living room and bedroom concentrations. However, there were only moderate correlations in concentrations between the different microenvironments and in some homes there was considerable variation between sampling sites. From the real-time measurements there seemed to be good agreement between concentrations measured in different rooms and in the cot and short-term peak concentrations at one sampling site were often mirrored at other sites. These results suggest that, although large variations in PM concentrations between rooms within homes can occur, a single monitoring station can provide a reasonable estimate of indoor concentrations.

Variability of particulate matter concentrations along roads and motorways determined by a moving measurement unit

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 (LASX) were installedin a van along with a global positioning system (GPS). Concentrations were measuredwith 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 andmass of particulate matter increase along with the degree of urbanisation, with number concentration being the more sensitive indicator. The lowest particle numbers and PM1-concentrations are encountered in a coastal andrural area: o5000 cm 3 and6 m gm 3 , respectively. The presence of sea-salt material along the NorthSea coast enhances PM>1-concentrations comparedto inlandlevels. High-particle numbers are encounteredon motorways correlating with traffic intensity; the largest average number concentration is measuredon the ring motorway aroundAmsterd am: about 160 000 cm 3 (traffic intensity 100 000 veh day 1 ). Peak values occur in tunnels where numbers exceed10 6 cm 3 . EnhancedPM 1 levels (i.e. larger than 9m gm 3 ) exist on motorways, major traffic roads and in tunnels. The concentrations of PM>1 appear rather uniformly distributed (below 6m gm 3 for most observations). On the urban scale, (large) spatial variations in concentration can be explainedby varying intensities of traffic andd riving patterns. The highest particle numbers are measuredwhile being in traffic congestions or when behind a heavy diesel-driven vehicle (up to 600 10 3 cm 3 ). Relatively high numbers are observedduring 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 backgroundareas. r 2004 Elsevier Ltd. All rights reserved.

A Small Whole-Body Exposure Chamber for Laboratory Use

With the development of transgenic and specialized mouse strains, there is an increased need for inhalation exposure systems designed for smaller exposure groups. An inhalation exposure chamber, designed specifically for the exposure of up to 40 mice, was characterized. The chamber was fabricated from 0.32-cm-thick (1 / 8 -in) aluminum sheets with outside dimensions of 61 cm long by 32 cm high by 34 cm deep, resulting in an internal volume of 65 L. Two stainless-steel open-mesh cages, separated by an absorbent barrier, can be stacked within the central portion of the chamber. Access is provided through a gasketed door with a safety-glass face. Tests were performed to determine the chamber leakage rate, degree of mixing, and spatial variation of two aerosols within the chamber. Results indicated that the fractional leakage rate was 0.0003 min -1, well below a reported criterion for an operating chamber. Chamber operation gave similar mixing performance with, or without, use of an interior fan. For aerosols with a mass median aerodynamic diameter (MMAD) of 2.56 µm and 3.14 µm, the spatial variation of particulate matter concentration resulted in coefficients of variation (CVs) of 4.8% and 11.0%, respectively. These CV values are comparable to those obtained from similar studies involving other inhalation exposure chambers.

Methodology for Siting Ambient Air Monitors at the Neighborhood Scale

In siting a monitor to measure compliance with U.S. National Ambient Air Quality Standards (NAAQS) for par-ticulate matter (PM), there is a need to characterize variations in PM concentration within a neighborhood-scale region to achieve monitor siting objectives. A simple methodology is provided here for the selection of a neighborhood-scale site for meeting either of the two objectives identified for PM monitoring. This methodology is based on analyzing middle-scale (from 100 to 500 m) data from within the area of interest. The required data can be obtained from widely available dispersion models and emissions databases. The performance of the siting methodology was evaluated in a neighborhood-scale field study conducted in Hudson County, NJ, to characterize the area’s inhalable particulate (PM10) concentrations. Air monitors were located within a 2- by 2-km area in the vicinity of the Lincoln Tunnel entrance in Hudson County. Results indicate the siting methodology performed well, providing a positive relationship between the predicted concentration rank at each site and the actual rank experienced during the field study. Also discussed are factors that adversely affected the predictive capabilities of the model.

Seasonal, interannual and decadal variations in particulate matter concentrations and composition in the subtropical North Pacific Ocean

Abstract The mean distributions of particulate carbon (PC), nitrogen (PN) and phosphorus (PP) in the euphotic zone (EZ) at Sta. ALOHA (22°45′N, 158°W) in the North Pacific Subtropical Gyre (NPSG) reveal a two-layered system with distinct upper (0–75 m) and lower (75–175 m) EZ dynamics. Particulate matter mean concentrations in the upper EZ were relatively constant with depth, and those in the lower EZ decreased significantly with increasing water depth. The vertical partitioning of particulate matter was approximately 60% in the upper EZ and 40% in the lower EZ. Significant temporal variability, both seasonal and interannual, was observed within both regions. PC and PN inventories in the upper EZ displayed a distinct annual cycle with variable interannual amplitude. The annual cycle was characterized by PC and PN maxima in summer and fall, and minima in winter. PP exhibited a smaller variation with season but also had a distinct wintertime minimum. These variations in particulate matter concentrations were accompanied by seasonal changes in elemental composition; summer and fall conditions were characterized by high C : P and N : P ratios exceeding 140 : 1 and 20 : 1, respectively. It is hypothesized that these concentration and composition patterns result from a net seasonal accumulation of non-living particulate matter throughout the summer and fall periods, and a rapid export during transition to winter conditions. Data also suggest that PN inventories in the NPSG have increased during the past three decades in response to changes in habitat, community composition or both. These temporally decoupled seasonal, interannual and decadal-scale ecological processes will complicate attempts to achieve mass balance or to derive mechanistic biogeochemical models.

Benthic storms in the Argentine Basin

Abstract The Argentine Basin is a region of large lateral gradients and extremely high concentrations and integrated loads of particulate matter (PM) in the abyssal nepheloid layer. The region also has large lateral variations in currents and surface and abyssal eddy kinetic energy. To investigate a suggested link between PM concentrations and eddy kinetic energy, transmissometers were attached to current meters moored at 10 m above the seafloor at five sites from the Argentine continental slope (1970 m) to the central basin (5045 m) from April 1987 to March 1988. Benthic storms (periods of high PM concentrations often associated with high current velocities) were recorded at all sites. The intensity of benthic storms (based on both frequency and elevated PM concentration) increased with distance from the margin, despite frequent periods where currents exceeded the expected erosion velocity near the margin. A good correlation was found between abyssal eddy kinetic energy (AEKE) and variations in PM concentration, except at the central basin site. At that site, a three month period of very high PM concentrations occurred with only low to moderate currents. The high PM concentrations may have resulted from the rapid input of low-density, organic-rich phytodetritus from a plankton bloom in surface waters.