Chemical Composition and Source Apportionment of PM25 Particles in the Sihwa Area,Korea

ABSTRACT

To investigate the chemical characteristics of fine particles in the Sihwa area, Korea, atmospheric aerosol samples were collected using a dichotomous PM₁₀ sampler and two URG PM_2.5 cyclone samplers during five intensive sampling periods between February 1998 and February 1999. The Inductively Coupled Plasma (ICP)-Atomic Emission Spectrometry (AES)/ICP-Mass Spectrometry (MS), ion chromatograph (IC), and thermal manganese dioxide oxidation (TMO) methods were used to analyze the trace elements, ionic species, and carbonaceous species, respectively. Backward trajectory analysis, factor analysis, and a chemical mass balance (CMB) model were used to estimate quantitatively source contributions to PM_{2 5} particles collected in the Sihwa area.

The results of PM_2.5 source apportionment using the CMB7 receptor model showed that (NH₄)₂SO₄ was, on average, the major contributor to PM_2.5 particles, followed by nontraffic organic carbon (OC) emission, NH₄NO₃, agricultural waste burning, motor vehicle emission, road dust, waste incineration, marine aerosol, and others. Here, the nontraffic OC sources include primary anthropogenic OC emitted from the industrial complex zone, secondary OC, and organic species from distant sources. The source impact of waste incineration emission became significant when the dominant wind directions were from southwest and west sectors during the sampling periods. It was found that PM_2.5 particles in the Sihwa area were influenced mainly by both anthropogenic local sources and long-range transport and transformation of air pollutants.     

Systematic Biases in Measured PM10 Values with U.S. Environmental Protection Agency-Approved Samplers at Owens Lake,California

ABSTRACT

From 1993 through 1998, Wedding or Graseby high-volume PM₁₀ samplers were collocated with tapered element oscillating microbalance (TEOM) samplers at three sites at Owens Lake, CA. The study area is heavily impacted by windblown dust from the dry Owens Lake bed, which was exposed as a result of water diversions to the city of Los Angeles. A dichotomous (dichot) sampler and three collocated Partisol samplers were added in 1995 and 1999, respectively. U.S. Environmental Protection Agency (EPA) operating procedures were followed for all samplers, except for a Wedding sampler that was not cleaned for the purpose of this study. On average, the TEOM and Partisol samplers agreed to within 6%, and the dichot, Graseby, and Wedding samplers measured lower PM₁₀ concentrations by about 10, 25, and 35%, respectively. Surprisingly, the “clean” Wedding sampler consistently measured the same concentration as the “dirty” Wedding sampler through 85 runs without cleaning. The finding that the Graseby and Wedding high-volume PM₁₀ samplers read consistently lower than the TEOM, Partisol, and dichot samplers at Owens Lake is consistent with PM₁₀ sampler comparisons done in other fugitive dust areas, and with wind tunnel tests showing that sampler cut points can be significantly lower than 10 um under certain conditions. However, these results are opposite of the bias found for TEOM samplers in areas that have significant amounts of volatile particles, where the TEOM reads low due to the vaporization of particles on the TEOM's heated filter. Coarse particles like fugitive dust are relatively unaffected by the filter temperature. This study shows that in the absence of volatile particles and in the presence of fugitive dust, a different systematic bias of up to 35% exists between samplers using dichot inlets and high-volume samplers, which may cause the Graseby and Wedding PM₁₀ samplers to undermeasure PM₁₀ by up to 35% when the PM₁₀ is predominantly from coarse particulate sources.     

Determination of PM2.5 Sulfate and Nitrate with a PC-BOSS Designed for Routine Sampling for Semi-Volatile Particulate Matter

ABSTRACT

Ambient particles contain substantial quantities of material that can be lost from the particles during sample collection on a filter. These include ammonium nitrate and semi-volatile organic compounds. As a result, the concentrations of these species are often significantly in error for results obtained with a filter pack sampler. The accurate measurement of these semi-volatile fine particulate species is essential for a complete understanding of the possible causes of health effects associated with exposure to fine particles. Past organic compound diffusion denuder samplers developed by the authors (e.g., the Brigham Young University Organic Sampling System [BOSS]) are not amenable to routine field use because of the need to independently determine the gas-phase semi-volatile organic material efficiency of the denuder for each sample. This problem has been eliminated using a combined virtual impactor, particle-concentrator inlet to provide a concentrated stream of 0.1-2.5-μm particles. This is followed by a BOSS diffusion denuder and filter packs to collect particles, including any semi-volatile species lost from the particles during sampling. The samp ler (Particle Concentrator-Brigham Young University Organic Sampling System [PC-BOSS]) contains a post-denuder multifilter pack unit to allow for the routine collection of several sequential samples. The PC-BOSS can be used for the determination of both fine particulate nitrate and semi-volatile organic material without significant “positive” or “negative” sampling artifacts. Validation of the sampler for the determination of PM_2.5 sulfate and nitrate based on comparison of results obtained at Riverside, CA with collocated PC-BOSS, annular denuder, and Chem Spec samplers indicates the PC-BOSS gives accurate results for these species with a precision of ±5-8%. An average of 33% of the PM_2.5 nitrate was lost from the particles during sampling for both denuder and single filter samplers.     

Performance Characteristics of PM10 Samplers under Calm Air Conditions

ABSTRACT

The size range of airborne particles that is closely related to specific deposition regions in the human respiratory tract and excess lung burden of these deposited particles is associated with disease. Size-selective sampling, therefore, needs to be performed to assess the related health risks. Performance criteria applied to these samplers must be well characterized in order to provide accurate and reliable results. The PM₁₀ samplers that have been used in place of the total suspended particulate samplers for the collection of ambient air particles are more relevant to potential inhalation hazards. In order to be certified, a PM₁₀ sampler must meet reliable performance specifications, primarily the aerosol penetration test with liquid and solid particles in a wind tunnel (wind speeds of 2, 8, and 24 km/hr). This testing is intended to assure reasonable accuracy in aerosol measurements. However, the sampler performance under calm air conditions has not been well studied.

In the present study, the sampling heads of three devices—the Harvard impactor, the Personal Environmental Monitor (PEM), and the Sierra Andersen model 241 dichotomous sampler PM₁₀ inlet head—were tested for aerosol separation efficiency. With the consideration of bias and imprecision of the measurements, five specimens of each type of sampler were chosen for performance testing, repeating the tests 5 times for each specimen. An ultrasonic atomizing nozzle was used to nebulize potassium sodium tartrate tetrahydrate and dioctyl phthalate particles as the solid and liquid challenge aerosols, respectively. The aerosol number concentrations and size distributions upstream and downstream of the samplers were measured by using an aerosizer calibrated against a settling velocity chamber. The results showed that among the samplers tested, the dichotomous sampler PM₁₀ inlet head had the best fit to the PM₁₀ convention, while the other two samplers not only appeared to have a steeper separation-curve slope but also had significant particle bounce when challenged with solid particles. Analysis of variance also confirmed the superiority of the dichotomous samplers. Surface-coating with oil or grease greatly reduced the problem of particle bounce.     

Particulate Matter in California: Part 1—Intercomparison of Several PM2.5, PM10–2.5, and PM10 Monitoring Networks

Abstract

It will be many years before the recently deployed network of fine particulate matter with an aerodynamic diameter less than 2.5 [H9262]m (PM_2.5) Federal Reference Method (FRM) samplers produces information on nonattainment areas, trends, and source impacts. However, data on PM_2.5 and its major constituents have been routinely collected in California for the past 20 years. The California Air Resources Board operated as many as 20 dichotomous (dichot) samplers for PM_2.5 and coarse PM (PM_10–2.5). The California Acid Deposition Monitoring Program (CADMP) collected 12-h-average PM_2.5 and PM₁₀ from 1988 to 1995 at ten urban and rural sites and 24-h-average PM_2.5 at five urban sites since 1995. Beginning in 1994, the Children’s Health Study collected 2-week averages of PM_2.5 in 12 communities in southern California using the Two-Week Sampler (TWS). Comparisons of collocated samples establish relationships between the dichot, CADMP, and TWS samplers and the 82-site network of PM_2.5 FRM samplers deployed since 1999 in California. PM mass data from the different monitoring programs have modest to high correlation to FRM mass data, fairly small systematic biases and negative proportional biases ranging from 7 to 22%. If the biases are taken into account, all of the programs should be considered comparable with the FRM program. Thus, historical data can be used to develop long-term PM trends in California.     

Effects of Wind Direction on Coarse and Fine Particulate Matter Concentrations in Southeast Kansas

Abstract

Field data for coarse particulate matter ([PM] PM₁₀) and fine particulate matter (PM_2.5) were collected at selected sites in Southeast Kansas from March 1999 to October 2000, using portable MiniVol particulate samplers. The purpose was to assess the influence on air quality of four industrial facilities that burn hazardous waste in the area located in the communities of Chanute, Independence, Fredonia, and Coffeyville. Both spatial and temporal variation were observed in the data. Variation because of sampling site was found to be statistically significant for PM₁₀ but not for PM_2.5. PM₁₀ concentrations were typically slightly higher at sites located within the four study communities than at background sites. Sampling sites were located north and south of the four targeted sources to provide upwind and downwind monitoring pairs. No statistically significant differences were found between upwind and downwind samples for either PM₁₀ or PM_2.5, indicating that the targeted sources did not contribute significantly to PM concentrations. Wind direction can frequently contribute to temporal variation in air pollutant concentrations and was investigated in this study. Sampling days were divided into four classifications: predominantly south winds, predominantly north winds, calm/variable winds, and winds from other directions. The effect of wind direction was found to be statistically significant for both PM₁₀ and PM_2.5. For both size ranges, PM concentrations were typically highest on days with predominantly south winds; days with calm/variable winds generally produced higher concentrations than did those with predominantly north winds or those with winds from “other” directions. The significant effect of wind direction suggests that regional sources may exert a large influence on PM concentrations in the area.     

Validity of Ambient Levels of Fine Particles as Surrogate for Personal Exposure to Outdoor Air Pollution—Results of the European EXPOLIS-EAS Study (Swiss Center Basel)

ABSTRACT

To evaluate the validity of fixed-site fine particle levels as exposure surrogates in air pollution epidemiology, we considered four indicator groups: (1) PM₂₅ total mass concentrations, (2) sulfur and potassium for regional air pollution, (3) lead and bromine for traffic-related particles, and (4) calcium for crustal particles. Using data from the European EXPOLIS (Air Pollution Exposure Distribution within Adult Urban Populations in Europe) study, we assessed the associations between 48-hr personal exposures and home outdoor levels of the indicators. Furthermore, within-city variability of fine particle levels was evaluated.

Personal exposures to PM_2.5 mass were not correlated to corresponding home outdoor levels (n = 44, r_{S (S)} =r o v ' Spearman (Sp) 0.07). In the group reporting neither relevant indoor sources nor relevant activities, personal exposures and home outdoor levels of sulfur were highly correlated (n = 40, r_Sp = 0.85). In contrast, the associations were weaker for traffic (Pb: n = 44, r_Sp = 0.53; Br: n = 44, r_Sp = 0.21) and crustal (Ca: n = 44, r_Sp = 0.12) indicators. This contrast is consistent with spatially homogeneous regional pollution and higher spatial variability of traffic and crustal indicators observed in Basel, Switzerland.

We conclude that for regional air pollution, fixed-site fine particle levels are valid exposure surrogates. For source-specific exposures, however, fixed-site data are probably not the optimal measure. Still, in air pollution epidemiology, ambient PM_2.5 levels may be more appropriate exposure estimates than total personal PM_2.5 exposure, since the latter reflects a mixture of indoor and outdoor sources.     

Techniques for High-Quality Ambient Coarse Particle Mass Measurements

ABSTRACT

Several recent studies have shown associations between ambient concentrations of particle mass (PM) and rates of morbidity and mortality in the general population. These studies have raised the issue of quality of coarse mass (CM, PM between 2.5 and 10 µm) data used for these purposes. CM data may have precision three or more times worse than the associated PM _2.5 or PM₁₀ data, depending on the measurement method, PM _2.5 to PM ₁₀ ratios, and CM concentrations. CM is measured either as the difference between collocated _PM10 and _PM2.5 samplers or more directly with a dichotomous (virtual impactor) sampler. CM precision for the difference method is degraded due to the increased errors inherent with using the difference between two independent measurements, as well as the high PM_2.5 to PM₁₀ ratios (and low CM concentrations) typical of the eastern United States. The dichotomous sampler (dichot) makes a more direct measurement of CM, but there is a potential for significant postexposure loss of particles from unoiled CM dichot filters, as well as uncertainties in the dichot’s CM channel enrichment factor. Compared to the dichot, low-volume inertial impactor samplers such as the Harvard Impactor (HI) or PM2.5 Federal Reference Method (FRM) are simpler to operate and maintain, provide sharper cut points, and do not require oiled filters to prevent loss of CM from the filter during transport. With the recent interest in CM spatial and temporal variability with respect to PM health effects, we have developed modifications to the HI PM method to provide measurements of 24-hour PM with estimated CM precision of better than 5% CV and r² higher than 0.95, primarily by lowering field blank variability and increasing gravimetric analytical precision. These high-precision PM techniques are not limited to the HI sampler; they can also be applied to the _PM2.5 FRM sampler. The measurement methods described here can be applied to future PM studies to avoid the potential problems with exposure assessment caused by CM measurements that have poor precision.     

Source Apportionment of Fine Particulate Matter in the Southeastern United States

Abstract

Particulate matter (PM) less than 2.5 μm in size (PM_2.5)source apportionment by chemical mass balance receptor modeling was performed to enhance regional characterization of source impacts in the southeastern United States. Secondary particles, such as NH₄HSO₄, (NH₄)₂SO₄,NH₄NO₃, and secondary organic carbon (OC) (SOC), formed by atmospheric photochemical reactions, contribute the majority (<50%) of ambient PM_2.5 with strong seasonality. Source apportionment results indicate that motor vehicle and biomass burning are the two main primary sources in the southeast, showing relatively more motor vehicle source impacts rather than biomass burning source impacts in populated urban areas and vice versa in less urbanized areas. Spatial distributions of primary source impacts show that each primary source has distinctively different spatial source impacts. Results also find impacts from shipping activities along the coast. Spatiotemporal correlations indicate that secondary particles are more regionally distributed, as are biomass burning and dust, whereas impacts of other primary sources are more local.     

Particulate organic compounds emitted from experimental wildland fires in a Mediterranean ecosystem

Fine (PM_2.5) and coarse (PM_2.5–10) smoke particles from controlled biomass burnings of a shrub-dominated forest in Lousã Mountain, Portugal, enabled the quantification by chromatographic techniques of several molecular tracers for the combustion of Mediterranean forest ecosystems, which could be conducive to source apportionment studies. The major organic components in the smoke samples were pyrolysates of vegetation cuticles, mainly comprising steradienes and sterol derivatives, carbohydrates from the breakdown of cellulose, aliphatic lipids from vegetation waxes and methoxyphenols from the lignin thermal degradation. Most of these compounds are chiefly found in fine particles. Polycyclic aromatic hydrocarbons (PAH) were also present as minor constituents. Anhydrosugar and PAH molecular diagnostic ratios were applied as source assignment tools. Some biomarkers are reported for the first time in biomass burning smoke.     

Is remaining indoors an effective way of reducing exposure to fine particulate matter during biomass burning events?

Bushfires, prescribed burns, and residential wood burning are significant sources of fine particles (aerodynamic diameter <2.5 μm; PM_2.5) affecting the health and well-being of many communities. Despite the lack of evidence, a common public health recommendation is to remain indoors, assuming that the home provides a protective barrier against ambient PM_2.5. The study aimed to assess to what extent houses provide protection against peak concentrations of outdoor PM_2.5 and whether remaining indoors is an effective way of reducing exposure to PM_2.5. The effectiveness of this strategy was evaluated by conducting simultaneous week-long indoor and outdoor measurements of PM_2.5 at 21 residences in regional areas of Victoria, Australia. During smoke plume events, remaining indoors protected residents from peak outdoor PM_2.5 concentrations, but the level of protection was highly variable, ranging from 12% to 76%. Housing stock (e.g., age of the house) and ventilation (e.g., having windows/doors open or closed) played a significant role in the infiltration of outdoor PM_2.5 indoors. The results also showed that leaving windows and doors closed once the smoke plume abates trapped PM_2.5 indoors and increased indoor exposure to PM_2.5. Furthermore, for approximately 50% of households, indoor sources such as cooking activities, smoking, and burning candles or incense contributed significantly to indoor PM_2.5.

Implications: Smoke from biomass burning sources can significantly impact on communities. Remaining indoors with windows and doors closed is a common recommendation by health authorities to minimize exposures to peak concentrations of fine particles during smoke plume events. Findings from this study have shown that the protection from fine particles in biomass burning smoke is highly variable among houses, with information on housing age and ventilation status providing an approximate assessment on the protection of a house. Leaving windows closed once a smoke plume abates traps particles indoors and increases exposures.     

Observations and Interpretations from the Canadian Fine Particle Monitoring Program

ABSTRACT

Canadian particle monitoring programs examining PM10, PM2.5, and particle composition have been in operation for over 10 years. Until recently, the measurements were manual/filter-based with 24-hr sample collection varying in frequency from daily to every sixth day, using GrasebyAnderson dichotomous samplers. In the past few years, these monitoring activities have been expanded to include hourly measurements using tapered element oscillating microbalances (TEOMs). This continuous monitoring program started operation focusing on PM_10, but now emphasizes PM_2.5 through the addition of more TEOMs and switching of the inlets of some of the existing units. The data from all of these measurement activities show that there are broad geographical differences and also local- to regional-scale spatial differences in mass and composition of PM2.5. Due to variations in sources, significantly different PM2.5 concentrations are not uncommon within the same city. Comparison of nearby urban and rural sites indicates that 30 and 40% of the PM_2.5 is from local urban sources in Montreal and Toronto, respectively. Hourly PM_2.5 measurements in Toronto suggest that vehicular emissions are an important contributor to urban PM_2.5. There has been a decreasing trend in urban PM_2.5, with annual average concentrations between the 1987–1990 and 1993–1995 periods decreasing by 11 to 39%, depending upon the site. The largest declines were in Montreal and Halifax, and the smallest decline was in Toronto. Comparison of 24-hr TEOM and manual dichotomous sampler PM_2.5 measurements from a site in Toronto indicates that the TEOM results in lower concentrations. The magnitude of this difference is relatively small in the warmer months, averaging about 12%. During the colder months the difference averages about 23%, but can be as large as 50%.     

Spatial differences in ambient coarse and fine particles in the Monterrey metropolitan area,Mexico: Implications for source contribution

The ambient air of the Monterrey Metropolitan Area (MMA) in Mexico frequently exhibits high levels of PM₁₀ and PM_2.5. However, no information exists on the chemical composition of coarse particles (PM_c = PM₁₀ – PM_2.5). A monitoring campaign was conducted during the summer of 2015, during which 24-hr average PM₁₀ and PM_2.5 samples were collected using high-volume filter-based instruments to chemically characterize the fine and coarse fractions of the PM. The collected samples were analyzed for anions (Cl^–, NO₃^–, SO₄^2–), cations (Na⁺, NH₄⁺, K⁺), organic carbon (OC), elemental carbon (EC), and 35 trace elements (Al to Pb). During the campaign, the average PM_2.5 concentrations did not showed significance differences among sampling sites, whereas the average PM_c concentrations did. In addition, the PM_c accounted for 75% to 90% of the PM₁₀ across the MMA. The average contribution of the main chemical species to the total mass indicated that geological material including Ca, Fe, Si, and Al (45%) and sulfates (11%) were the principal components of PM_c, whereas sulfates (54%) and organic matter (30%) were the principal components of PM_2.5. The OC-to-EC ratio for PM_c ranged from 4.4 to 13, whereas that for PM_2.5 ranged from 3.97 to 6.08. The estimated contribution of Secondary Organic Aerosol (SOA) to the total mass of organic aerosol in PM_2.5 was estimated to be around 70–80%; for PM_c, the contribution was lower (20–50%). The enrichment factors (EF) for most of the trace elements exhibited high values for PM_2.5 (EF: 10–1000) and low values for PM_c (EF: 1–10). Given the high contribution of crustal elements and the high values of EFs, PM_c is heavily influenced by soil resuspension and PM_2.5 by anthropogenic sources. Finally, the airborne particles found in the eastern region of the MMA were chemically distinguishable from those in its western region.

Implications: Concentration and chemical composition patterns of fine and coarse particles can vary significantly across the MMA. Public policy solutions have to be built based on these observations. There is clear evidence that the spatial variations in the MMA’s coarse fractions are influenced by clearly recognizable primary emission sources, while fine particles exhibit a homogeneous concentration field and a clear spatial pattern of increasing secondary contributions. Important reductions in the coarse fraction can come from primary particles’ emission controls; for fine particles, control of gaseous precursors—particularly sulfur-containing species and organic compounds—should be considered.     

Laboratory and Field Evaluation of Measurement Methods for One-Hour Exposures to O3, PM25, and CO

ABSTRACT

While researchers have linked acute (less than 12-hr) ambient O₃, PM₂₅, and CO concentrations to a variety of adverse health effects, few studies have characterized short-term exposures to these air pollutants, in part due to the lack of sensitive, accurate, and precise sampling technologies. In this paper, we present results from the laboratory and field evaluation of several new (or modified) samplers used in the “roll-around” system (RAS), which was developed to measure 1-hr O₃, PM₂₅, and CO exposures simultaneously. All the field evaluation data were collected during two sampling seasons: the summer of 1998 and the winter of 1999.

To measure 1-hr O₃ exposures, a new active O₃ sampler was developed that uses two nitrite-coated filters to measure O₃ concentrations. Laboratory chamber tests found that the active O₃ sampler performed extremely well, with a collection efficiency of 0.96 that did not vary with temperature or relative humidity (RH). In field collocation comparisons with a reference UV photometric monitor, the active O₃ sampler had an effective collection efficiency ranging between 0.92 and 0.96 and a precision for 1-hr measurements ranging between 4 and 6 parts per billion (ppb). The limits of detection (LOD) of this method were 9 ppb-hr for the chamber tests and ~16 ppb-hr for the field comparison tests.

PM_2.5 and CO concentrations were measured using modified continuous monitors—the DustTrak and the Langan, respectively. A size-selective inlet and a Nafion dryer were placed upstream of the DustTrak inlet to remove particles with aerodynamic diameters greater than 2.5 um and to dry particles prior to the measurements, respectively. During the field validation tests, the DustTrak consistently reported higher PM_2.5 concentrations than those obtained by the collocated 12-hr PM_{2 5} PEM samples, by approximately a factor of 2. After the DustTrak response was corrected (correction factor of 2.07 in the summer and 2.02 in the winter), measurements obtained using these methods agreed well with R² values of 0.87 in the summer and 0.81 in the winter. The results showed that the DustTrak can be used along with integrated measurements to measure the temporal and spatial variation in PM_{2 5} exposures. Finally, during the field validation tests, CO concentrations measured using the Langan were strongly correlated with those obtained using the reference method when the CO levels were above the LOD of the instrument [~1 part per million (ppm)].     

Characterisation of particulate exposure during fireworks displays

Little is known about the level and content of exposure to fine particles (PM_2.5) among persons who attend fireworks displays and those who live nearby. An evaluation of the levels of PM_2.5 and their elemental content was carried out during the nine launches of the 2007 Montréal International Fireworks Competition. For each event, a prediction of the location of the firework plume was obtained from the Canadian Meteorological Centre (CMC) of the Meteorological Service of Canada. PM_2.5 was measured continuously with a photometer (Sidepak?, TSI) within the predicted plume location (“predicted sites”), and integrated samples were collected using portable personal samplers. An additional sampler was located on a nearby roof (“fixed site”). The elemental composition of the collected PM_2.5 samples from the “predicted sites” was determined using both a non-destructive energy dispersive ED-XRF method and an ICP-MS method with a near-total microwave-assisted acid digestion. The elemental composition of the “fixed site” samples was determined by the ICP-MS with the near-total digestion method. The highest PM_2.5 levels reached nearly 10 000 μg m^?3, roughly 1000 times background levels. Elements such as K, Cl, Al, Mg and Ti were markedly higher in plume-exposed filters. This study shows that 1) persons in the plume and in close proximity to the launch site may be exposed to extremely high levels of PM_2.5 for the duration of the display and, 2) that the plume contains specific elements for which little is known of their acute cardio-respiratory toxicity.     

Source Profiles of Particulate Matter Emissions from a Pilot-Scale Boiler Burning North American Coal Blends

ABSTRACT

Recent awareness of suspected adverse health effects from ambient particulate matter (PM) emission has prompted publication of new standards for fine PM with aerodynamic diameter less than 2.5 μm (PM_2.5). However, scientific data on fine PM emissions from various point sources and their characteristics are very limited. Source apportionment methods are applied to identify contributions of individual regional sources to tropospheric particulate concentrations. The existing industrial database developed using traditional source measurement techniques provides total emission rates only, with no details on chemical nature or size characteristics of particulates. This database is inadequate, in current form, to address source-receptor relationships.

A source dilution system was developed for sampling and characterization of total PM, PM_2.5, and PM₁₀ (i.e., PM with aerodynamic diameter less than 10 μm) from residual oil and coal combustion. This new system has automatic control capabilities for key parameters, such as relative humidity (RH), temperature, and sample dilution. During optimization of the prototype equipment, three North American coal blends were burned using a 0.7-megawatt thermal (MW_t) pulverized coal-fired, pilot-scale boiler. Characteristic emission profiles, including PM_2.5 and total PM soluble acids, and elemental and carbon concentrations for three coal blends are presented.     

Source identification of nickel in TSP and PM2.5 in Tokyo,Japan

This study investigates the source identification of nickel in the aerosol of the Tokyo metropolitan area. TSP and PM_2.5 samples were collected daily from August to November 2004. The samples were examined by means of the water-extraction method, followed by elemental analysis and SEM/EDX analysis. We distinguished two types of atmospheric nickel sources in the studied area: (1) particles derived from heavy oil combustion, distributed mostly in fine particles such as PM_2.5, relatively water-soluble, and containing vanadium and (2) particles derived from mechanical abrasion/erosion of metallic surfaces, distributed in coarse particles such as TSP, relatively water-insoluble, and containing chromium.     

Field performance of dichotomous sequential PM air samplers

For over one year, the Environmental Protection Commission of Hillsborough County (EPCHC) in Tampa, Florida, operated two dichotomous sequential particulate matter air samplers collocated with a manual Federal Reference Method (FRM) air sampler at a waterfront site on Tampa Bay. The FRM was alternately configured as a PM_2.5, then as a PM₁₀ sampler. For the dichotomous sampler measurements, daily 24-h integrated PM_2.5 and PM_10–2.5 ambient air samples were collected at a total flow rate of 16.7 l min⁻¹. A virtual impactor split the air into flow rates of 1.67 and 15.0 l min⁻¹ onto PM_10–2.5 and PM_2.5 47-mm diameter PTFE^® filters, respectively. Between the two dichotomous air samplers, the average concentration, relative bias and relative precision were 13.3 μg m⁻³, 0.02% and 5.2% for PM_2.5 concentrations (n=282), and 12.3 μg m⁻³, 3.9% and 7.7% for PM_10–2.5 concentrations (n=282). FRM measurements were alternate day 24-h integrated PM_2.5 or PM₁₀ ambient air samples collected onto 47-mm diameter PTFE^® filters at a flow rate of 16.7 l min⁻¹. Between a dichotomous and a PM_2.5 FRM air sampler, the average concentration, relative bias and relative precision were 12.4 μg m⁻³, −5.6% and 8.2% (n=43); and between a dichotomous and a PM₁₀ FRM air sampler, the average concentration, relative bias and relative precision were 25.7 μg m⁻³, −4.0% and 5.8% (n=102). The PM_2.5 concentration measurement standard errors were 0.95, 0.79 and 1.02 μg m⁻³; for PM₁₀ the standard errors were 1.06, 1.59, and 1.70 μg m⁻³ for two dichotomous and one FRM samplers, respectively, which indicate the dichotomous samplers have superior technical merit. These results reveal the potential for the dichotomous sequential air sampler to replace the combination of the PM_2.5 and PM₁₀ FRM air samplers, offering the capability of making simultaneous, self-consistent determinations of these particulate matter fractions in a routine ambient monitoring mode.     

Source apportionment of fine particulate matter (PM2.5) at a rural Ohio River Valley site

Twenty four-hour averaged concentrations of fine particulate matter were collected at Athens, OH between March 2004 and November 2005 in an effort to characterize the nature of PM_2.5 and apportion its sources. PM_2.5 samples were chemically analyzed and positive matrix factorization was applied to this speciation data to identify the probable sources. PMF arrived at a 7-factor model to most accurately apportion sources of the PM_2.5 observed at Athens. Conditional probability function (CPF) and potential source contribution function (PSCF) were applied to the identified sources to investigate the geographical location of these sources. Secondary sulfate source dominated the contributions with a total contribution of 62.6% with the primary and secondary organic source following second with 19.9%. Secondary nitrate contributed a total of 6.5% with the steel production source and Pb- and Zn-source coming in at 3.1% and 2.9%, respectively. Crustal and mobile sources were small contributors (2.5% each) of PM_2.5 to the Athens region. The secondary sulfate, secondary organic and nitrate portrayed a clear seasonal nature with the sulfate and secondary organic peaking in the warm months and the nitrate reaching a high in the cold months. The high percentage of secondary sulfate observed at a rural site like Athens suggests the involvement of regional transport mechanisms.     

Temporal variations of fine and coarse particulate matter sources in Jeddah,Saudi Arabia

This study provides the first comprehensive analysis of the seasonal variations and weekday/weekend differences in fine (aerodynamic diameter <2.5 μm; PM_2.5) and coarse (aerodynamic diameter 2.5–10 μm; PM_2.5–10) particulate matter mass concentrations, elemental constituents, and potential source origins in Jeddah, Saudi Arabia. Air quality samples were collected over 1 yr, from June 2011 to May 2012 at a frequency of three times per week, and analyzed. The average mass concentrations of PM_2.5 (21.9 μg/m³) and PM₁₀ (107.8 μg/m³) during the sampling period exceeded the recommended annual average levels by the World Health Organization (WHO) for PM_2.5 (10 μg/m³) and PM₁₀ (20 μg/m³), respectively. Similar to other Middle Eastern locales, PM_2.5–10 is the prevailing mass component of atmospheric particulate matter at Jeddah, accounting for approximately 80% of the PM₁₀ mass. Considerations of enrichment factors, absolute principal component analysis (APCA), concentration roses, and backward trajectories identified the following source categories for both PM_2.5 and PM_2.5–10: (1) soil/road dust, (2) incineration, and (3) traffic; and for PM_2.5 only, (4) residual oil burning. Soil/road dust accounted for a major portion of both the PM_2.5 (27%) and PM_2.5–10 (77%) mass, and the largest source contributor for PM_2.5 was from residual oil burning (63%). Temporal variations of PM_2.5–10 and PM_2.5 were observed, with the elevated concentration levels observed for mass during the spring (due to increased dust storm frequency) and on weekdays (due to increased traffic). The predominant role of windblown soil and road dust in both the PM_2.5 and PM_2.5–10 masses in this city may have implications regarding the toxicity of these particles versus those in the Western world where most PM health assessments have been made in the past. These results support the need for region-specific epidemiological investigations to be conducted and considered in future PM standard setting.

Implications: Temporal variations of fine and coarse PM mass, elemental constituents, and sources were examined in Jeddah, Saudi Arabia, for the first time. The main source of PM_2.5–10 is natural windblown soil and road dust, whereas the predominant source of PM_2.5 is residual oil burning, generated from the port and oil refinery located west of the air sampler, suggesting that targeted emission controls could significantly improve the air quality in the city. The compositional differences point to a need for health effect studies to be conducted in this region, so as to directly assess the applicability of the existing guidelines to the Middle East air pollution.