Sources Of Fine Particulate Matter Research Articles

Fine Particulate Matter Source Apportionment Following a Large Woodstove Changeout Program in Libby, Montana

Before a community-wide woodstove changeout program, a chemical mass balance (CMB) source apportionment study was conducted in Libby, MT, during the winter of 2003–2004 to identify the sources of fine particulate matter (PM2.5) within the valley. Results from this study showed that residential woodstoves were the major source, contributing approximately 80% of the ambient PM2.5 throughout the winter months. In an effort to lower the ambient PM2.5, a large woodstove changeout program was conducted in Libby from 2005 to 2007 in which nearly 1200 old woodstoves were changed out with cleaner burning models. During the winter of 2007–2008, a follow-up CMB source apportionment study was conducted to evaluate the effectiveness of the changeout. Results from this study showed that average winter PM2.5 mass was reduced by 20%, and woodsmoke-related PM2.5 (as identified by the CMB model) was reduced by 28% when compared with the pre-changeout winter of 2003– 2004. These results suggest that a woodstove changeout can be an effective tool in reducing ambient levels of PM2.5 in woodstove-impacted communities.

Contribution of fine particulate matter sources to indoor exposure in bars, restaurants, and cafes

This study investigated the contribution of sources and establishment characteristics, on the exposure to fine particulate matter (PM(2.5)) in the non-smoking sections of bars, cafes, and restaurants in central Zurich. PM(2.5)-exposure was determined with a nephelometer. A random sample of hospitality establishments was investigated on all weekdays, from morning until midnight. Each visit lasted 30 min. Numbers of smokers and other sources, such as candles and cooking processes, were recorded, as were seats, open windows, and open doors. Ambient air pollution data were obtained from public authorities. Data were analysed using robust MM regression. Over 14 warm, sunny days, 102 establishments were measured. Average establishment PM(2.5) concentrations were 64.7 microg/m(3) (s.d. = 73.2 microg/m(3), 30-min maximum 452.2 microg/m(3)). PM(2.5) was significantly associated with the number of smokers, percentage of seats occupied by smokers, and outdoor PM. Each smoker increased PM(2.5) on average by 15 microg/m(3). No associations were found with other sources, open doors or open windows. Bars had more smoking guests and showed significantly higher concentrations than restaurants and cafes. Smokers were the most important PM(2.5)-source in hospitality establishments, while outdoor PM defined the baseline. Concentrations are expected to be even higher during colder, unpleasant times of the year. Smokers and ambient air pollution are the most important sources of fine airborne particulate matter (PM(2.5)) in the non-smoking sections of bars, restaurants, and cafes. Other sources do not significantly contribute to PM(2.5)-levels, while opening doors and windows is not an efficient means of removing pollutants. First, this demonstrates the impact that even a few smokers can have in affecting particle levels. Second, it implies that creating non-smoking sections, and using natural ventilation, is not sufficient to bring PM(2.5) to levels that imply no harm for employees and non-smoking clients.

Assessment of personal exposure to inhalable indoor and outdoor particulate matter for student residents of an academic campus (IIT-Kanpur)

Human exposure to particulate matter can have significant harmful effects on the respiratory and cardiovascular system. These effects vary with number, size, and chemical composition of particulate matter, which vary significantly with space and time. The Indian Institute of Technology–Kanpur (IITK), Kanpur, India, is a relatively clean academic campus in the northwest of a heavily polluted city, Kanpur. The major objectives of the study were to evaluate total exposure of fine and coarse fractions of PM10 to a typical IITK student resident in different indoor microenvironments within the campus; to evaluate personal exposure to student residents during outdoor trips; and to evaluate personal exposure to a typical student resident carrying out routine activities. In order to account for all the sources of particulate matter exposure, measurements on several different days during the pre-monsoon season were carried out in the most common indoor microenvironments in the campus and during outdoor trips outside the campus. A 15-channel optical particle counter (model 1.108, GRIMM) was used to measure continuous real-time particle size distribution from 0.3 to 20 μm diameter. Using this instrument, exposure for 1 h at different indoor microenvironments was determined. Both the effects of location and activity, which, in turn, account for specific indoor sources and number of occupants, respectively, were carefully evaluated. Re-suspension of particles due to movement of people was found to be a major source of coarse particulate matter exposure. On the other hand, combustion sources led to elevated fine particulate levels. Chalk dust was found to be the major source of fine particulate matter in classrooms. Similar results on other sources of particulate matter are discussed in the paper. To assess the personal average size resolved particulate exposure on a student making a day trip outside the campus, study trips to most common public places in the city in a commonly preferred vehicle were made. Striking correlations between sources/activities and increase in fine and/or coarse particle concentration were clearly visible. To investigate the daily personal exposure and its relation to the activities of a typical student residing in the campus, a 24-h exposure study was done on a student who maintained a time-activity diary. The results provide insight into possible sources and their interaction with human activities in modifying the human exposure levels. A comparison between different microenvironments has been attempted for the first time in an Indian scenario using a real-time aerosol measuring instrument.

Multi-criteria ranking and source apportionment of fine particulate matter in Brisbane, Australia

Environmental context. There are serious global concerns about the environmental and health effects of atmospheric air pollutants. However, estimates of pollutants from measurements made in the proximity of a source do not always represent the ultimate atmospheric concentrations. Therefore alternative methods of attributing pollutants to sources, and estimating their contributions to atmospheric concentrations, as demonstrated in the current work, will become an increasingly important area of environmental research. Abstract. This paper reports the application of multicriteria decision making techniques, Preference Ranking Organisation Methods for Enrichment Evaluation (PROMETHEE) and Graphical Analysis for Interactive Assistance (GAIA), and receptor models, principal component analysis/absolute principal component scores (PCA/APCS) and positive matrix factorisation (PMF), to data from an air monitoring site located on the campus of Queensland University of Technology in Brisbane, Australia and operated by Queensland Environmental Protection Agency (QEPA). The data consisted of the concentrations of 21 chemical species and meteorological data collected between 1995 and 2003. PROMETHEE/GAIA separated the samples into those collected when leaded and unleaded petrol were used to power vehicles in the region. The number and source profiles of the factors obtained from PCA/APCS and PMF analyses were compared. There are noticeable differences in the outcomes possibly because of the non-negative constraints imposed on the PMF analysis. Whereas PCA/APCS identified 6 sources, PMF reduced the data to 9 factors. Each factor had distinctive compositions that suggested that motor vehicle emissions, controlled burning of forests, secondary sulfate, sea salt and soil were the most important sources of fine particulate matter at the site. The most plausible locations of the sources were identified by combining the results obtained from the receptor models with meteorological data. The study demonstrated the potential benefits of combining results from multi-criteria decision making analysis with those from receptor models in order to gain insights into information that could enhance the development of air pollution control measures.

Source Apportionment of Particulate Matter in the U.S. and Associations with Lung Inflammatory Markers

Size-fractionated particulate matter (PM) samples were collected from six U.S. cities and chemically analyzed as part of the Multiple Air Pollutant Study. Particles were administered to cultured lung cells and the production of three different proinflammatory markers was measured to explore the association between the health effect markers and PM. Ultrafine, fine, and coarse PM samples were collected between December 2003 and May 2004 over a 4-wk period in each city. Filters were pooled for each city and the PM samples were extracted then analyzed for trace metals, ions, and elemental carbon. Particle extracts were applied to cultured human primary airway epithelial cells, and the secreted levels of interleukin-8 (IL-8), heme oxygenase-1, and cyclooxygenase-2 were measured 1 and 24 h following exposure. Fine PM sources were quantified by the chemical mass balance (CMB) model. The relationship between toxicological measures, PM sources, and individual species were evaluated using linear regression. Ultrafine and fine PM mass were associated with increases in IL-8 (r2 = .80 for ultrafine and r2 = .52 for fine). Sources of fine PM and their relative contributions varied across the sampling sites and a strong linear association was observed between IL-8 and secondary sulfate from coal combustion (r2 = .79). Ultrafine vanadium, lead, copper, and sulfate were also associated with increases in IL-8. Increases in inflammatory markers were not observed for coarse PM mass and source markers. These findings suggest that certain PM size fractions and sources are associated with markers of lung injury or inflammation.

Fine Particulate Matter Source Apportionment for the Chemical Speciation Trends Network Site at Birmingham, Alabama, Using Positive Matrix Factorization

The Positive Matrix Factorization (PMF) receptor model version 1.1 was used with data from the fine particulate matter (PM2.5) Chemical Speciation Trends Network (STN) to estimate source contributions to ambient PM2.5 in a highly industrialized urban setting in the southeastern United States. Model results consistently resolved 10 factors that are interpreted as two secondary, five industrial, one motor vehicle, one road dust, and one biomass burning sources. The STN dataset is generally not corrected for field blank levels, which are significant in the case of organic carbon (OC). Estimation of primary OC using the elemental carbon (EC) tracer method applied on a seasonal basis significantly improved the model’s performance. Uniform increase of input data uncertainty and exclusion of a few outlier samples (associated with high potassium) further improved the model results. However, it was found that most PMF factors did not cleanly represent single source types and instead are “contaminated” by other sources, a situation that might be improved by controlling rotational ambiguity within the model. Secondary particulate matter formed by atmospheric processes, such as sulfate and secondary OC, contribute the majority of ambient PM2.5 and exhibit strong seasonality (37 ± 10% winter vs. 55 ± 16% summer average). Motor vehicle emissions constitute the biggest primary PM2.5 mass contribution with almost 25 ± 2% long-term average and winter maximum of 29 ± 11%. PM2.5 contributions from the five identified industrial sources vary little with season and average 14 ± 1.3%. In summary, this study demonstrates the utility of the EC tracer method to effectively blank-correct the OC concentrations in the STN dataset. In addition, examination of the effect of input uncertainty estimates on model results indicates that the estimated uncertainties currently being provided with the STN data may be somewhat lower than the levels needed for optimum modeling results.

Supplemental Material to "Fine Particulate Matter Source Apportionment for the Chemical Speciation Trends Network Site at Birmingham, Alabama, Using Positive Matrix Factorization" by Baumann et al.

Supplemental Material to "Fine Particulate Matter Source Apportionment for the Chemical Speciation Trends Network Site at Birmingham, Alabama, Using Positive Matrix Factorization" by Baumann et al.

Compilation and Assessment of Recent Positive Matrix Factorization and UNMIX Receptor Model Studies on Fine Particulate Matter Source Apportionment for the Eastern United States

In 1997, the U.S. Environmental Protection Agency (EPA) revised its particulate matter standards to include an annual standard for fine particulate matter (PM2.5; 15 μg/ m3) and a 24-hr standard (65 μg/m3). The 24-hr standard was lowered to 35 μg/m3 in 2006 in an effort to further reduce overall ambient PM2.5 concentrations. Identifying and quantifying sources of particulate matter affecting a particular location through source apportionment methods is now an important component of the information available to decision makers when evaluating the new standards. This literature compilation summarizes a subset of the source apportionment research and general findings on fine particulate matter in the eastern half of the United States using Positive Matrix Factorization. The results between studies are generally comparable when comparable datasets are used; however, methodologies vary considerably. Commonly identified source categories include: secondary sulfate/coal burning (sometimes over 50% of total mass), secondary organic carbon/mobile sources, crustal sources, biomass burning, nitrate, various industrial processes, and sea salt. The source apportionment tools and methodologies have passed the proof-of-concept stage and are now being used to understand the ambient composition of particulate matter for sites across the United States and the spatial relationship of sources to the receptor. Recommendations are made for further and standardized method development for source apportionment studies, and specific research areas of interest for the eastern United States are proposed.

Traffic-Related Atmospheric Pollutants Levels during Pregnancy and Offspring’s Term Birth Weight: A Study Relying on a Land-Use Regression Exposure Model

BackgroundSome studies have suggested that particulate matter (PM) levels during pregnancy may be associated with birth weight. Road traffic is a major source of fine PM (PM with aero-dynamic diameter < 2.5 μm; PM2.5).ObjectiveWe determined to characterize the influence of maternal exposure to atmospheric pollutants due to road traffic and urban activities on offspring term birth weight.MethodsWomen from a birth cohort [the LISA (Influences of Lifestyle Related Factors on the Human Immune System and Development of Allergies in Children) cohort] who delivered a non-premature baby with a birth weight > 2,500 g in Munich metropolitan area were included. We assessed PM2.5, PM2.5 absorbance (which depends on the blackness of PM2.5, a marker of traffic-related air pollution), and nitrogen dioxide levels using a land-use regression model, taking into account the type and length of roads, population density, land coverage around the home address, and temporal variations in pollution during pregnancy. Using Poisson regression, we estimated prevalence ratios (PR) of birth weight < 3,000 g, adjusted for gestational duration, sex, maternal smoking, height, weight, and education.ResultsExposure was defined for 1,016 births. Taking the lowest quartile of exposure during pregnancy as a reference, the PR of birth weight < 3,000 g associated with the highest quartile was 1.7 for PM2.5 [95% confidence interval (CI), 1.2–2.7], 1.8 for PM2.5 absorbance (95% CI, 1.1–2.7), and 1.2 for NO2 (95% CI, 0.7–1.7). The PR associated with an increase of 1 μg/m3 in PM2.5 levels was 1.13 (95% CI, 1.00–1.29).ConclusionIncreases in PM2.5 levels and PM2.5 absorbance were associated with decreases in term birth weight. Traffic-related air pollutants may have adverse effects on birth weight.

Analysis and Apportionment of Organic Carbon and Fine Particulate Matter Sources at Multiple Sites in the Midwestern United States

Speciated fine particulate matter (PM2.5) data collected as part of the Speciation Trends Network at four sites in the Midwest (Detroit, MI; Cincinnati, OH; Indianapolis, IN; and Northbrook, IL) and as part of the Interagency Monitoring of Protected Visual Environments program at the rural Bondville, IL, site were analyzed to understand sources contributing to organic carbon (OC) and PM2.5 mass. Positive matrix factorization (PMF) was applied to available data collected from January 2002 through March 2005, and seven to nine factors were identified at each site. Common factors at all of the sites included mobile (gasoline)/secondary organic aerosols with high OC, diesel with a high elemental carbon/OC ratio (only at the urban sites), secondary sulfate, secondary nitrate, soil, and biomass burning. Identified industrial factors included copper smelting (North–brook, Indianapolis, and Bondville), steel/manufacturing with iron (Northbrook), industrial zinc (North–brook, Cincinnati, Indianapolis, and Detroit), metal plating with chromium and nickel (Detroit, Indianapolis, and Bondville), mixed industrial with copper and iron (Cincinnati), and limestone with calcium and iron (Bondville). PMF results, on average, accounted for 96% of the measured PM2.5 mass at each site; residuals were consistently within tolerance (±3), and goodness–of–fit (Q) was acceptable. Potential source contribution function analysis helped identify regional and local impacts of the identified source types. Secondary sulfate and soil factors showed regional characteristics at each site, whereas industrial sources typically appeared to be locally influenced. These regional factors contributed approximately one third of the total PM2.5 mass, on average, whereas local mobile and industrial sources contributed to the remaining mass. Mobile sources were a major contributor (55–76% at the urban sites) to OC mass, generally with at least twice as much mass from nondiesel sources as from diesel. Regional OC associated with secondary sulfate and soil was generally low.

Source Apportionment of Molecular Markers and Organic Aerosol. 2. Biomass Smoke

Chemical mass balance analysis was performed using a large dataset of molecular marker concentrations to estimate the contribution of biomass smoke to ambient organic carbon (OC) and fine particle mass in Pittsburgh, Pennsylvania. Source profiles were selected based on detailed comparisons between the ambient data and a large number of published profiles. The fall and winter data were analyzed with fireplace and woodstove source profiles, and open burning profiles were used to analyze the spring and summer data. At the upper limit, biomass smoke is estimated to contribute on average 520+/-140 ng-C m(-3) or 14.5% of the ambient OC in the fall, 210+/-85 ng-C m(-3) or 10% of the ambient OC in the winter, and 60 + 21 ng-C/m(-3) or 2% of the ambient OC in the spring and summer. In the fall and winter, there is large day-to-day variability in the amount of OC apportioned to biomass smoke. The levels of biomass smoke in Pittsburgh are much lower than in some other areas of the United States, indicating significant regional variability in the importance of biomass combustion as a source of fine particulate matter. The calculations face two major sources of uncertainty. First, the ambient ratios of levoglucosan, resin acids, and syringhaldehyde concentrations are highly variable implying that numerous sources with distinct source profiles contribute to ambient marker concentrations. Therefore, in contrast to previous CMB analyses, we find that at least three distinct biomass smoke source profiles must be included in the CMB model to explain this variability. Second, the marker-to-OC ratios of available biomass smoke profiles are highly variable. This variability introduces uncertainty of more than a factor of 2 in the amount of ambient OC apportioned to biomass smoke by different statistically acceptable CMB solutions. The marker-to-OC ratios of source profiles are critical parameters to consider when evaluating CMB solutions.

Source Apportionment of Fine Particulate Matter in the United States and Associations With Lung Inflammatory Markers IL-8, COX-2, and HO-1

SAB4-PD-03 Introduction: Associations are well established between particulate matter (PM) mass concentrations and increased human mortality and morbidity. The toxicity of PM may depend on the PM source and composition of PM, which will vary depending on the sampling site. The association between fine PM sources and 3 lung inflammatory markers (interleukin-8, cyclooxygenase-2, and heme oxygenase-1) was evaluated in multiple cities with contrasting PM sources as part of the Multiple Pollutant Study (MAPS). Methods: Fine particles were collected in 6 sites in the United States during 2003 to 2004. Sampling sites included Washington (Seattle), Utah (Salt Lake City), Arizona (Phoenix), and New York (Hunter College, Sterling Forest, and South Bronx). One-week samples (24 hours a day) were collected at each site over a 4-week period using a High Volume Cascade Impactor. Trace metals were measured by Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES) and ions were measured by Ion Chromatography (IC). A chemical mass balance (CMB) model was used to quantify the sources impacting each sampling site. Particles were applied to cultured human primary airway epithelial cells and the secretion of interleukin-8 (IL-8) was measured 24 hours later by enzyme-linked immunosorbent assay (ELISA). Heme oxygenase-1 (HO-1) and cyclooxygenase-2 (COX-2) levels were quantified by real-time reverse transcriptase polymerase chain reaction (RT-PCR). Results: The sources of fine PM and their relative contributions varied across the sampling sites: mobile sources (4%–43%), residual oil combustion (1%–4%), coal combustion (19%–53%), lead smelting (<1%), oil refinery (<1%), wood combustion (8%–54%), soil dust (3%–4%), and secondary nitrate (8%–36%). Strong linear associations were observed between IL-8 and residual oil combustion (r2 = 0.84) in addition to coal combustion (r2 = 0.70). COX-2 exhibited weak linear correlations between residual oil combustion and coal combustion (r2 = 0.38 for each source). A strong linear association was observed between HO-1 and oil refineries (r2 = 0.99). It should be noted that residual oil combustion was only present in the eastern U.S. sites (n = 3) and oil refineries were only present in the western U.S sites (n = 3). Discussion and Conclusions: The inflammatory markers analyzed yield varying health responses to sources. IL-8 and COX-2 are correlated with the same sources, coal combustion and residual oil combustion, although at differing levels. In contrast, HO-1 had no significant correlation with these sources but rather was strongly correlated with oil refineries. Combustion and industrial sources appear to elicit an inflammatory response that is consistent with previous health studies.

Gaseous and Particulate Emissions from Prescribed Burning in Georgia

Prescribed burning is a significant source of fine particulate matter (PM2.5) in the southeastern United States. However, limited data exist on the emission characteristics from this source. Various organic and inorganic compounds both in the gas and particle phase were measured in the emissions of prescribed burnings conducted at two pine-dominated forest areas in Georgia. The measurements of volatile organic compounds (VOCs) and PM2.5 allowed the determination of emission factors for the flaming and smoldering stages of prescribed burnings. The VOC emission factors from smoldering were distinctly higher than those from flaming except for ethene, ethyne, and organic nitrate compounds. VOC emission factors show that emissions of certain aromatic compounds and terpenes such as alpha and beta-pinenes, which are important precursors for secondary organic aerosol (SOA), are much higher from active prescribed burnings than from fireplace wood and laboratory open burning studies. Levoglucosan is the major particulate organic compound (POC) emitted for all these studies, though its emission relative to total organic carbon (mg/g OC) differs significantly. Furthermore, cholesterol, an important fingerprint for meat cooking, was observed only in our in situ study indicating a significant release from the soil and soil organisms during open burning. Source apportionment of ambient primary fine particulate OC measured at two urban receptor locations 20-25 km downwind yields 74 +/- 11% during and immediately after the burns using our new in situ profile. In comparison with the previous source profile from laboratory simulations, however, this OC contribution is on average 27 +/- 5% lower.

Prescribed Burns and Wildfires in Colorado: Impacts of Mitigation Measures on Indoor Air Particulate Matter

Wildfires and prescribed burns are receiving increasing attention as sources of fine particulate matter (PM2.5). The goal of this research project was to understand the impact of mitigation strategies for residences impacted by scheduled prescribed burns and wildfires. Pairs of residences were solicited to have PM2.5 concentrations monitored inside and outside of their houses during four fires. The effect of using air cleaners on indoor PM2.5 was investigated, as well as the effect of keeping windows closed. Appropriately sized air cleaners were provided to one of each pair of residences; occupants of all of the residences were asked to keep windows shut and minimize opening of exterior doors. Additionally, residents were asked to record all of the activities that may be a source of particulate matter, such as cooking and cleaning. Measurements were made during one prescribed burn and three wildfires during the 2002 fire season. Outdoor 24‐hr average PM2.5 concentrations ranging from 6 to 38 µg/m3 were measured during the fires, compared with levels of 2–5 µg/m3 during background measurements when no fires were burning. During the fires, PM2.5 was <3 µg/m3 inside all of the houses with air cleaners installed. This corresponds with a decrease of 63–88% in homes with the air cleaners operating when compared with homes without air cleaners. In the homes without the air cleaners, measured indoor concentrations were 58–100% of the concentrations measured outdoors.

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.

Chase Studies of Particulate Emissions from in-use New York City Vehicles

Emissions from motor vehicles are a significant source of fine particulate matter (PM) and gaseous pollutants in urban environments. Few studies have characterized both gaseous and PM emissions from individual in-use vehicles under real-world driving conditions. Here we describe chase vehicle studies in which on-road emissions from individual vehicles were measured in real time within seconds of their emission. This work uses an Aerodyne aerosol mass spectrometer (AMS) to provide size-resolved and chemically resolved characterization of the nonrefractory portion of the emitted PM; refractory materials such as elemental carbon (EC) were not measured in this study. The AMS, together with other gas-phase and particle instrumentation, was deployed on the Aerodyne Research Inc. (ARI) mobile laboratory, which was used to “chase” the target vehicles. Tailpipe emission indices of the targeted vehicles were obtained by referencing the measured nonrefractory particulate mass loading to the instantaneous CO2 measured simultaneously in the plume. During these studies, nonrefractory PM1.0 (NRPM1) emission indices for a representative fraction of the New York City Metropolitan Transit Authority (MTA) bus fleet were determined. Diesel bus emissions ranged from 0.10 g NRPM1/kg fuel to 0.23 g NRPM1/kg, depending on the type of engine used by the bus. The average NRPM1 emission index of diesel-powered buses using Continuously Regenerating Technology (CRT™) trap systems was 0.052 g NRPM1/kg fuel. Buses fueled by compressed natural gas (CNG) had an average emission index of 0.034 g NRPM1/kg Fuel. The mass spectra of the nonrefractory diesel aerosol components measured by the AMS were dominated by lubricating oil spectral signatures. Mass-weighted size distributions of the particles in fresh diesel exhaust plumes peak at vacuum aerodynamic diameters around 90 nm with a typical full width at half maximum of 60 nm.

Characterization of Inorganic Particulate Matter from Residential Combustion of Pelletized Biomass Fuels

The increased focus on potential adverse health effects associated with exposure to ambient particulate matter (PM) motivates a careful characterization of particle emissions from different sources. Combustion is a major anthropogenic source of fine PM, and, in urban areas, traditional residential wood combustion can be a major contributor. New and upgraded biomass fuels have become more common, and fuel pellets are especially well-suited for the residential market. The objective of the present work was to determine the mass size distributions, elemental distributions, and inorganic-phase distributions of PM from different residential combustion appliances and pelletized biomass fuels. In addition, chemical equilibrium model calculations of the combustion process were used to interpret the experimental findings. Six different typical pellet fuels were combusted in three different commercial pellet burners (10−15 kW). The experiments were performed in a newly designed experimental setup that enables constant-volume sampling. Total-PM mass concentrations were measured using conventional filters, and the fractions of products of incomplete combustion and inorganic material were thermally determined. Particle mass size distributions were determined using a 13-step low-pressure cascade impactor with a precyclone. The PM was analyzed for morphology (using environmental scanning electron microscopy, ESEM), elemental composition (using energy-dispersive spectroscopy, EDS), and crystalline phases (using X-ray diffractometry, XRD). For complementary chemical structural characterization, time-of-flight secondary ion mass spectrometry (TOF−SIMS), X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) spectroscopy were also used. The emitted particles were mainly found in the fine (<1 μm) mode with mass median aerodynamic diameters of 0.20−0.39 μm and an average PM1 of 89.5% ± 7.4% of total PM. Minor coarse-mode fractions (>1 μm) were present primarily in the experiments with bark and logging residues. Relatively large and varying amounts (28%−92%) were determined to be products of incomplete combustion. The inorganic elemental compositions of the fine particles were dominated by potassium, chlorine, and sulfur, with minor amounts of sodium and zinc. The dominating alkali phase was KCl, with minor but varying amounts of K3Na(SO4)2 and, in some cases, also K2SO4. The results showed that zinc is almost fully volatilized, subsequently and presumably forming a more complex solid phase than that previously suggested (ZnO). However, the formation mechanism and exact phase identification remain to be elucidated. With some constrains, the results also showed that the amounts and speciation of the inorganic PM seemed to be quite similar to that predicted by chemical equilibrium calculations.

Measurement of PM 2.5 emission potential from soil using the UC Davis resuspension test chamber

Human health effects have been linked to airborne concentrations of fine particulate matter. One source of fine particulate matter in the atmosphere is resuspended soil dust from a variety of activities, including agricultural operations. We have established a method to measure the potential of soil to emit fugitive dust in the PM 10 or PM 2.5 size range. The method is repeatable, and provides an index of PM 10 or PM 2.5 dust that is highly correlated to the soil texture. The ratio of the PM 2.5 Index to the PM 10 Index produced by this method is similar to field observations of ambient PM 2.5 and PM 10 concentrations downwind of agricultural operations in the San Joaquin Valley of California. The PM 2.5 or PM 10 Index will be a more useful parameter to estimate the potential of a soil to emit fugitive dust than the currently used dry silt content of soil. Research is currently underway to relate the PM 10 and PM 2.5 Index to measured emission factors, accounting for soil moisture and type of agricultural operation, so that a more reliable predictive equation can be developed for agricultural practices.

Hydrologic Impacts of Disturbed Lands Treated with Dust Suppressants

This study presents research on changes in hydrologic characteristics of disturbed land surfaces that have been treated with dust suppressants. Disturbed land surfaces, such as construction sites and unpaved roads, are sources of fine particulate matter. The application of dust suppressants affects the runoff characteristics as well as the water quality of the runoff. The changes in runoff characteristics were investigated in the field using a rainfall simulator on plots treated with 11 different dust suppressants. The rainfall simulation system was able to provide a uniform distribution of rainfall over a 2.4×2.4 m (approximately) plot at relatively low rainfall intensities (21 mm/h). Results of the study indicate changes in runoff rates and volume, and the timing of runoff initiation. The majority of the plots had higher runoff volumes and an earlier time of runoff initiation as compared to the control plot. The total suspended solids in the runoff were reduced for the majority of the plots. Extrapolati...

Fine particulate matter source attribution for Southeast Texas using 14C/13C ratios

Radiocarbon analyses of fine particulate matter samples collected during the summer of 2000 in southeast Texas indicate that a substantial fraction of the aerosol carbon at an urban/suburban site (27–73%) and at a rural, forested site (44–77%) was modern carbon. Data from emission inventories and additional ambient measurements indicate that the most likely sources of this modern carbon are biomass burning fires and biogenic secondary organic aerosol.