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  • Identifying and quantifying secondhand smoke in source and receptor rooms: logistic regression and chemical mass balance approaches. Indoor air Dacunto, P. J., Cheng, K., Acevedo-Bolton, V., Jiang, R., Klepeis, N. E., Repace, J. L., Ott, W. R., Hildemann, L. M. 2014; 24 (1): 59-70

    Abstract

    Identifying and quantifying secondhand tobacco smoke (SHS) that drifts between multiunit homes is critical to assessing exposure. Twenty-three different gaseous and particulate measurements were taken during controlled emissions from smoked cigarettes and six other common indoor source types in 60 single-room and 13 two-room experiments. We used measurements from the 60 single-room experiments for (i) the fitting of logistic regression models to predict the likelihood of SHS and (ii) the creation of source profiles for chemical mass balance (CMB) analysis to estimate source apportionment. We then applied these regression models and source profiles to the independent data set of 13 two-room experiments. Several logistic regression models correctly predicted the presence of cigarette smoke more than 80% of the time in both source and receptor rooms, with one model correct in 100% of applicable cases. CMB analysis of the source room provided significant PM2.5 concentration estimates of all true sources in 9 of 13 experiments and was half-correct (i.e., included an erroneous source or missed a true source) in the remaining four. In the receptor room, CMB provided significant estimates of all true sources in 9 of 13 experiments and was half-correct in another two.

    View details for DOI 10.1111/ina.12049

    View details for PubMedID 23631597

  • Outdoor fine and ultrafine particle measurements at six bus stops with smoking on two California arterial highways-Results of a pilot study JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION Ott, W. R., Acevedo-Bolton, V., Cheng, K., Jiang, R., Klepeis, N. E., Hildemann, L. M. 2014; 64 (1): 47-60
  • Identifying and quantifying secondhand smoke in multiunit homes with tobacco smoke odor complaints ATMOSPHERIC ENVIRONMENT Dacunto, P. J., Cheng, K., Acevedo-Bolton, V., Klepeis, N. E., Repace, J. L., Ott, W. R., Hildemann, L. M. 2013; 71: 399-407
  • Experimental study on visible-light induced photocatalytic oxidation of gaseous formaldehyde by polyester fiber supported photocatalysts CHEMICAL ENGINEERING JOURNAL Han, Z., Chang, V., Wang, X., Lim, T., Hildemann, L. 2013; 218: 9-18
  • Controlled Experiments Measuring Personal Exposure to PM2.5 in Close Proximity to Cigarette Smoking. Indoor air Acevedo-Bolton, V., Ott, W. R., Cheng, K. C., Jiang, R. T., Klepeis, N. E., Hildemann, L. M. 2013

    Abstract

    Few measurements of exposure to secondhand smoke (SHS) in close proximity to a smoker are available. Recent health studies have demonstrated an association between acute (< 2 h) exposures to high concentrations of SHS and increased risk for cardiovascular and respiratory disease. We performed 15 experiments inside naturally-ventilated homes and 16 in outdoor locations, each with 2-4 nonsmokers sitting near a cigarette smoker. The smoker's and nonsmokers' real-time exposures to PM2.5 from SHS were measured by using TSI SidePak monitors to sample their breathing zones. In 87% of the residential indoor experiments, the smoker received the highest average exposure to SHS, with PM2.5 concentrations ranging from 50-630 ?g/m(3) . During the active smoking period, individual nonsmokers sitting within ~1 m of a smoker had average SHS exposures ranging from negligible up to >160 ?g/m(3) of PM2.5 . The average incremental exposure of the nonsmokers was higher indoors (42 ?g/m(3) , n = 35) than outdoors (29 ?g/m(3) , n = 47), but the overall indoor and outdoor frequency distributions were similar. The 10-s PM2.5 averages during the smoking periods showed great variability, with multiple high concentrations of short duration (microplumes) both indoors and outdoors. This article is protected by copyright. All rights reserved.

    View details for PubMedID 23808850

  • Real-time particle monitor calibration factors and PM2.5 emission factors for multiple indoor sources ENVIRONMENTAL SCIENCE-PROCESSES & IMPACTS Dacunto, P. J., Cheng, K., Acevedo-Bolton, V., Jiang, R., Klepeis, N. E., Repace, J. L., Ott, W. R., Hildemann, L. M. 2013; 15 (8): 1511-1519

    Abstract

    Indoor sources can greatly contribute to personal exposure to particulate matter less than 2.5 μm in diameter (PM2.5). To accurately assess PM2.5 mass emission factors and concentrations, real-time particle monitors must be calibrated for individual sources. Sixty-six experiments were conducted with a common, real-time laser photometer (TSI SidePak™ Model AM510 Personal Aerosol Monitor) and a filter-based PM2.5 gravimetric sampler to quantify the monitor calibration factors (CFs), and to estimate emission factors for common indoor sources including cigarettes, incense, cooking, candles, and fireplaces. Calibration factors for these indoor sources were all significantly less than the factory-set CF of 1.0, ranging from 0.32 (cigarette smoke) to 0.70 (hamburger). Stick incense had a CF of 0.35, while fireplace emissions ranged from 0.44-0.47. Cooking source CFs ranged from 0.41 (fried bacon) to 0.65-0.70 (fried pork chops, salmon, and hamburger). The CFs of combined sources (e.g., cooking and cigarette emissions mixed) were linear combinations of the CFs of the component sources. The highest PM2.5 emission factors per time period were from burned foods and fireplaces (15-16 mg min(-1)), and the lowest from cooking foods such as pizza and ground beef (0.1-0.2 mg min(-1)).

    View details for DOI 10.1039/c3em00209h

    View details for Web of Science ID 000322177300004

    View details for PubMedID 23784066

  • Preparation of TiO2-Coated Polyester Fiber Filter by Spray-Coating and Its Photocatalytic Degradation of Gaseous Formaldehyde AEROSOL AND AIR QUALITY RESEARCH Han, Z., Chang, V. W., Zhang, L., Tse, M. S., Tan, O. K., Hildemann, L. M. 2012; 12 (6): 1327-1335
  • Low demand for nontraditional cookstove technologies PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Mobarak, A. M., Dwivedi, P., Bailis, R., Hildemann, L., Miller, G. 2012; 109 (27): 10815-10820

    Abstract

    Biomass combustion with traditional cookstoves causes substantial environmental and health harm. Nontraditional cookstove technologies can be efficacious in reducing this adverse impact, but they are adopted and used at puzzlingly low rates. This study analyzes the determinants of low demand for nontraditional cookstoves in rural Bangladesh by using both stated preference (from a nationally representative survey of rural women) and revealed preference (assessed by conducting a cluster-randomized trial of cookstove prices) approaches. We find consistent evidence across both analyses suggesting that the women in rural Bangladesh do not perceive indoor air pollution as a significant health hazard, prioritize other basic developmental needs over nontraditional cookstoves, and overwhelmingly rely on a free traditional cookstove technology and are therefore not willing to pay much for a new nontraditional cookstove. Efforts to improve health and abate environmental harm by promoting nontraditional cookstoves may be more successful by designing and disseminating nontraditional cookstoves with features valued more highly by users, such as reduction of operating costs, even when those features are not directly related to the cookstoves' health and environmental impacts.

    View details for DOI 10.1073/pnas.1115571109

    View details for Web of Science ID 000306641100027

    View details for PubMedID 22689941

  • Measurement of the proximity effect for indoor air pollutant sources in two homes JOURNAL OF ENVIRONMENTAL MONITORING Acevedo-Bolton, V., Cheng, K., Jiang, R., Ott, W. R., Klepeis, N. E., Hildemann, L. M. 2012; 14 (1): 94-104

    Abstract

    Personal exposure to air pollutants can be substantially higher in close proximity to an active source due to non-instantaneous mixing of emissions. The research presented in this paper quantifies this proximity effect for a non-buoyant source in 2 naturally ventilated homes in Northern California (CA), assessing its spatial and temporal variation and the influence of factors such as ventilation rate on its magnitude. To quantify how proximity to residential sources of indoor air pollutants affects human exposure, we performed 16 separate monitoring experiments in the living rooms of two detached single-family homes. CO (as a tracer gas) was released from a point source in the center of the room at a controlled emission rate for 5-12 h per experiment, while an array of 30-37 real-time monitors simultaneously measured CO concentrations with 15 s time resolution at radial distances ranging from 0.25-5 m under a range of ventilation conditions. Concentrations measured in close proximity (within 1 m) to the source were highly variable, with 5 min averages that typically varied by >100-fold. This variability was due to short-duration (<1 min) pollutant concentration peaks ("microplumes") that were frequently recorded in close proximity to the source. We decomposed the random microplume component from the total concentrations by subtracting predicted concentrations that assumed uniform, instantaneous mixing within the room and found that these microplumes can be modeled using a 3-parameter lognormal distribution. Average concentrations measured within 0.25 m of the source were 6-20 times as high as the predicted well-mixed concentrations.

    View details for DOI 10.1039/c1em10521c

    View details for Web of Science ID 000298855800012

    View details for PubMedID 22068152

  • Determination of response of real-time SidePak AM510 monitor to secondhand smoke, other common indoor aerosols, and outdoor aerosol JOURNAL OF ENVIRONMENTAL MONITORING Jiang, R., Acevedo-Bolton, V., Cheng, K., Klepeis, N. E., Ott, W. R., Hildemann, L. M. 2011; 13 (6): 1695-1702

    Abstract

    The amount of light scattered by airborne particles inside an aerosol photometer will vary not only with the mass concentration, but also with particle properties such as size, shape, and composition. This study conducted controlled experiments to compare the measurements of a real-time photometer, the SidePak AM510 monitor (SidePak), with gravimetric mass. PM sources tested were outdoor aerosols, and four indoor combustion sources: cigarettes, incense, wood chips, and toasting bread. The calibration factor for rescaling the SidePak measurements to agree with gravimetric mass was similar for the cigarette and incense sources, but different for burning wood chips and toasting bread. The calibration factors for ambient urban aerosols differed substantially from day to day, due to variations in the sources and composition of outdoor PM. A field evaluation inside a casino with active smokers yielded calibration factors consistent with those obtained in the controlled experiments with cigarette smoke.

    View details for DOI 10.1039/c0em00732c

    View details for Web of Science ID 000291403300019

    View details for PubMedID 21589975

  • Fine particle air pollution and secondhand smoke exposures and risks inside 66 US casinos ENVIRONMENTAL RESEARCH Repace, J. L., Jiang, R., Acevedo-Bolton, V., Cheng, K., Klepeis, N. E., Ott, W. R., Hildemann, L. M. 2011; 111 (4): 473-484

    Abstract

    Smoking bans often exempt casinos, exposing occupants to fine particles (PM(2.5)) from secondhand smoke. We quantified the relative contributions to PM(2.5) from both secondhand smoke and infiltrating outdoor sources in US casinos. We measured real-time PM(2.5), particulate polycyclic aromatic hydrocarbons (PPAH), and carbon dioxide (CO(2)) (as an index of ventilation rate) inside and outside 8 casinos in Reno, Nevada. We combined these data with data from previous studies, yielding a total of 66 US casinos with smoking in California, Delaware, Nevada, New Jersey, and Pennsylvania, developing PM(2.5) frequency distributions, with 3 nonsmoking casinos for comparison. Geometric means for PM(2.5) were 53.8 ?g/m(3) (range 18.5-205 ?g/m(3)) inside smoking casinos, 4.3 ?g/m(3) (range 0.26-29.7 ?g/m(3)) outside those casinos, and 3.1 ?g/m(3) (range 0.6-9 ?g/m(3)) inside 3 nonsmoking casinos. In a subset of 21 Reno and Las Vegas smoking casinos, PM(2.5) in gaming areas averaged 45.2 ?g/m(3) (95% CI, 37.7-52.7 ?g/m(3)); adjacent nonsmoking casino restaurants averaged 27.2 ?g/m(3) (95% CI, 17.5-36.9 ?g/m(3)), while PM(2.5) outside the casinos averaged 3.9 ?g/m(3) (95% CI, 2.5-5.3 ?g/m(3)). For a subset of 10 Nevada and Pennsylvania smoking casinos, incremental (indoor-outdoor) PM(2.5) was correlated with incremental PPAH (R(2)=0.79), with ventilation rate-adjusted smoker density (R(2)=0.73), and with smoker density (R(2)=0.60), but not with ventilation rates (R(2)=0.15). PPAH levels in 8 smoking casinos in 3 states averaged 4 times outdoors. The nonsmoking casinos' PM(2.5) (n=3) did not differ from outdoor levels, nor did their PPAH (n=2). Incremental PM(2.5) from secondhand smoke in approximately half the smoking casinos exceeded a level known to produce cardiovascular morbidity in nonsmokers after less than 2h of exposure, posing acute health risks to patrons and workers. Casino ventilation and air cleaning practices failed to control secondhand smoke PM(2.5). Drifting PM(2.5) from secondhand smoke contaminated unseparated nonsmoking areas. Smoke-free casinos reduced PM(2.5) to the same low levels found outdoors.

    View details for DOI 10.1016/j.envres.2011.02.007

    View details for Web of Science ID 000290141600001

    View details for PubMedID 21440253

  • Modeling Exposure Close to Air Pollution Sources in Naturally Ventilated Residences: Association of Turbulent Diffusion Coefficient with Air Change Rate ENVIRONMENTAL SCIENCE & TECHNOLOGY Cheng, K., Acevedo-Bolton, V., Jiang, R., Klepeis, N. E., Ott, W. R., Fringer, O. B., Hildemann, L. M. 2011; 45 (9): 4016-4022

    Abstract

    For modeling exposure close to an indoor air pollution source, an isotropic turbulent diffusion coefficient is used to represent the average spread of emissions. However, its magnitude indoors has been difficult to assess experimentally due to limitations in the number of monitors available. We used 30-37 real-time monitors to simultaneously measure CO at different angles and distances from a continuous indoor point source. For 11 experiments involving two houses, with natural ventilation conditions ranging from <0.2 to >5 air changes per h, an eddy diffusion model was used to estimate the turbulent diffusion coefficients, which ranged from 0.001 to 0.013 m² s?¹. The model reproduced observed concentrations with reasonable accuracy over radial distances of 0.25-5.0 m. The air change rate, as measured using a SF? tracer gas release, showed a significant positive linear correlation with the air mixing rate, defined as the turbulent diffusion coefficient divided by a squared length scale representing the room size. The ability to estimate the indoor turbulent diffusion coefficient using two readily measurable parameters (air change rate and room dimensions) is useful for accurately modeling exposures in close proximity to an indoor pollution source.

    View details for DOI 10.1021/es103080p

    View details for Web of Science ID 000289819400033

    View details for PubMedID 21456572

  • Measurement of fine particles and smoking activity in a statewide survey of 36 California Indian casinos JOURNAL OF EXPOSURE SCIENCE AND ENVIRONMENTAL EPIDEMIOLOGY Jiang, R., Cheng, K., Acevedo-Bolton, V., Klepeis, N. E., Repace, J. L., Ott, W. R., Hildemann, L. M. 2011; 21 (1): 31-41

    Abstract

    Despite California's 1994 statewide smoking ban, exposure to secondhand smoke (SHS) continues in California's Indian casinos. Few data are available on exposure to airborne fine particles (PM?.?) in casinos, especially on a statewide basis. We sought to measure PM?.? concentrations in Indian casinos widely distributed across California, exploring differences due to casino size, separation of smoking and non-smoking areas, and area smoker density. A selection of 36 out of the 58 Indian casinos throughout California were each visited for 1-3?h on weekend or holiday evenings, using two or more concealed monitors to measure PM?.? concentrations every 10?s. For each casino, the physical dimensions and the number of patrons and smokers were estimated. As a preliminary assessment of representativeness, we also measured eight casinos in Reno, NV. The average PM?.? concentration for the smoking slot machine areas (63??g/m³) was nine times as high as outdoors (7??g/m³), whereas casino non-smoking restaurants (29??g/m³) were four times as high. Levels in non-smoking slot machine areas varied: complete physical separation reduced concentrations almost to outdoor levels, but two other separation types had mean levels that were 13 and 29??g/m³, respectively, higher than outdoors. Elevated PM?.? concentrations in casinos can be attributed primarily to SHS. Average PM?.? concentrations during 0.5-1?h visits to smoking areas exceeded 35??g/m³ for 90% of the casino visits.

    View details for DOI 10.1038/jes.2009.75

    View details for Web of Science ID 000285452900006

    View details for PubMedID 20160761

  • Contributions of Foot Traffic and Outdoor Concentrations to Indoor Airborne Aspergillus AEROSOL SCIENCE AND TECHNOLOGY Goebes, M. D., Boehm, A. B., Hildemann, L. M. 2011; 45 (3): 352-363
  • Association of size-resolved airborne particles with foot traffic inside a carpeted hallway ATMOSPHERIC ENVIRONMENT Cheng, K., Goebes, M. D., Hildemann, L. M. 2010; 44 (16): 2062-2066
  • Measuring and modeling the composition and temperature-dependence of surface tension for organic solutions ATMOSPHERIC ENVIRONMENT Aumann, E., Hildemann, L. M., Tabazadeh, A. 2010; 44 (3): 329-337
  • Model-based reconstruction of the time response of electrochemical air pollutant monitors to rapidly varying concentrations JOURNAL OF ENVIRONMENTAL MONITORING Cheng, K., Acevedo-Bolton, V., Jiang, R., Klepeis, N. E., Ott, W. R., Hildemann, L. M. 2010; 12 (4): 846-853

    Abstract

    Electrochemical sensors are commonly used to measure concentrations of gaseous air pollutants in real time, especially for personal exposure investigations. The monitors are small, portable, and have suitable response times for estimating time-averaged concentrations. However, for transient exposures to air pollutants lasting only seconds to minutes, a non-instantaneous time response can cause measured values to diverge from actual input concentrations, especially when the pollutant fluctuations are pronounced and rapid. Using 38 Langan carbon monoxide (CO) monitors, which can be set to log data every 2 s, we found electrochemical sensor response times of 30-50 s. We derived a simple model based on Fick's Law to reconstruct a close to accurate time series from logged data. Starting with experimentally measured data for repetitive step input signals of alternating high and low CO concentrations, we were able to reconstruct a much improved 2-s concentration time series using the model. We also utilized the model to examine errors in monitor measurements for different averaging times. By selecting the averaging time based on the response time of the monitor, the error between actual and measured pollutant levels can be minimized. The methodology presented in this study is useful when aiming to accurately determine a time series of rapidly time-varying concentrations, such as for locations close to an active point source or near moving traffic.

    View details for DOI 10.1039/b921806h

    View details for Web of Science ID 000276532100007

    View details for PubMedID 20383365

  • The Effects of Human Activities on Exposure to Particulate Matter and Bioaerosols in Residential Homes ENVIRONMENTAL SCIENCE & TECHNOLOGY Chen, Q., Hildemann, L. M. 2009; 43 (13): 4641-4646

    Abstract

    Indoor and outdoor airborne particle mass, protein, endotoxin and (1 --> 3)-beta-D-glucan in three size fractions (PM2.5, PM10, and TSP) were measured in ten single-family homes, along with quantifying household activities in the sampling room. Correlations between human activity levels and elevations in the indoor concentrations of particles and biomarkers were evaluated using four approaches for distinguishing activity levels: diurnal differences, the number of occupants, self-estimated occupancy, and activity strength. The concentrations of particles, protein, endotoxin and (1 --> 3)-beta-D-glucan in all three size fractions (PM < 2.5 microm, PM10-2.5, and PM >10 microm) were found, in most cases, to be significantly elevated during the day, and with higher activity levels in the room. The coarser fractions of particle mass and bioaerosols were more strongly correlated with human activity levels. Activity strength was the most statistically robust measure for relating human activities to indoor bioaerosol levels. While self-estimated activity and analysis of diurnal differences both offer reasonable (but not perfect) alternatives to activity strength, the number of occupants appears to be a weaker indicator for homes.

    View details for DOI 10.1021/es802296j

    View details for Web of Science ID 000267435500007

    View details for PubMedID 19673245

  • Wind Tunnel Measurements of the Dilution of Tailpipe Emissions Downstream of a Car, a Light-Duty Truck, and a Heavy-Duty Truck Tractor Head JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION Chang, V. W., Hildemann, L. M., Chang, C. 2009; 59 (6): 704-714

    Abstract

    The particle and gaseous pollutants in vehicle exhaust emissions undergo rapid dilution with ambient air after exiting the tailpipe. The rate and extent of this dilution can greatly affect both the size evolution of primary exhaust particles and the potential for formation of ultrafine particles. Dilution ratios were measured inside of a wind tunnel in the region immediately downstream of the tailpipe using model vehicles (approximately one-fifth to one-seventh scale models) representing a light-duty truck, a passenger car, and a heavy-duty tractor head (without the trailer). A tracer gas (ethene) was released at a measured flow rate from the tailpipe, and 60 sampling probes placed downstream of the vehicle simultaneously sampled gas tracer concentrations in the near-wake (first few vehicle heights) and far-wake regions (beyond 10 vehicle heights). Tests using different tunnel wind speeds show the range of dilution ratios that can be expected as a function of vehicle type and downstream distance (i.e., time). The vehicle shape quite strongly influences dilution profiles in the near-wake region but is much less important in the far-wake region. The tractor generally produces higher dilution rates than the automobile and light-duty truck under comparable conditions.

    View details for DOI 10.3155/1047-3289.59.6.704

    View details for Web of Science ID 000266797400006

    View details for PubMedID 19603738

  • Dilution Rates for Tailpipe Emissions: Effects of Vehicle Shape, Tailpipe Position, and Exhaust Velocity JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION Chang, V. W., Hildemann, L. M., Chang, C. 2009; 59 (6): 715-724

    Abstract

    The rate at which motor vehicle exhaust undergoes dilution with ambient air will greatly affect the size distribution characteristics of the particulate emissions. Wind tunnel experiments were conducted to investigate the impacts of vehicle shape, tailpipe orientation, and exhaust exit velocity on the dilution profiles under steady driving conditions for three model vehicles: a light-duty truck, a passenger car, and a heavy-duty tractor head. A three dimensional array of 60 sensors provided simultaneous measurements of dilution ratios for the emissions in the near- and far-wake regions downstream of the vehicle. The processes underlying the observations were investigated via nondimensionalization. Many of the trends seen substantially downstream can be well generalized using a simple nondimensionalization technique; however, this is not true in the near-wake region (within a downstream distance equivalent to a few vehicle heights). In the near-wake region, using the vehicle width and length to normalize for the vehicle shape is not enough to fully account for the variations seen. Including the exhaust flow rate in the nondimensionalization process is effective further downwind but does not adequately capture the complexity in the near-wake region. Tailpipe orientation and location are also shown to be influential factors affecting the near-wake dilution characteristics.

    View details for DOI 10.3155/1047-3289.59.6.715

    View details for Web of Science ID 000266797400007

    View details for PubMedID 19603739

  • Effect of interior door position on room-to-room differences in residential pollutant concentrations after short-term releases ATMOSPHERIC ENVIRONMENT Ferro, A. R., Klepeis, N. E., Ott, W. R., Nazaroff, W. W., Hildemann, L. M., Switzer, P. 2009; 43 (3): 706-714
  • Size-Resolved Concentrations of Particulate Matter and Bioaerosols Inside versus Outside of Homes AEROSOL SCIENCE AND TECHNOLOGY Chen, Q., Hildemann, L. M. 2009; 43 (7): 699-713
  • Effect of building construction on Aspergillus concentrations in a hospital INFECTION CONTROL AND HOSPITAL EPIDEMIOLOGY Goebes, M. D., Baron, E. J., Mathews, K. L., Hildemann, L. M. 2008; 29 (5): 462-464

    Abstract

    Air samples taken in a hospital undergoing construction and analyzed with a quantitative polymerase chain reaction (qPCR) assay for the Aspergillus genus did not show elevated concentrations of Aspergillus or particulate matter with a diameter of 5 microm or less in patient areas. Air samples from the construction zone indicated the containment system, which used polyethylene film barrier and negative pressure, was effective.

    View details for DOI 10.1086/587189

    View details for Web of Science ID 000254898800016

    View details for PubMedID 18419373

  • ENHANCED ACUTE RESPONSES IN AN EXPERIMENTAL EXPOSURE MODEL TO BIOMASS SMOKE INHALATION IN CHRONIC OBSTRUCTIVE PULMONARY DISEASE EXPERIMENTAL LUNG RESEARCH Mattson, J. D., Haus, B. M., Desai, B., Ott, W., Basham, B., Agrawal, M., Ding, W., Hildemann, L. M., Abitorabi, K. M., Canfield, J., Mak, G., Guvenc-Tuncturk, S., Malefyt, R. d., McClanahan, T. K., Fick, R. B., Kuschner, W. G. 2008; 34 (10): 631-662

    Abstract

    Chronic obstructive pulmonary diseases (COPD) may increase air pollution-related mortality. The relationship of immune mechanisms to mortality caused by fine particulates in healthy and COPD populations is incompletely understood. The objective of this study was to determine whether fine particulates from a single biomass fuel alter stress and inflammation biomarkers in people with COPD. Healthy and COPD subjects were exposed to smoke in a controlled indoor setting. Immune responses were quantified by measuring cell surface marker expression with flow-cytometric analysis and mRNA levels with quantitative reverse transcriptase-polymerase chain reactions in whole blood before and after exposure. Preexposure COPD subjects had more leukocytes, mainly CD14(+) monocytes and neutrophils, but fewer CD3(+) T cells. Fifty-seven of 186 genes were differentially expressed between healthy and COPD subjects' peripheral blood mononuclear cells (PBMCs). Of these, only nuclear factor (NF)-kappa B1, TIMP-1, TIMP-2, and Duffy genes were up-regulated in COPD subjects. At 4 hours post smoke exposure, monocyte levels decreased only in healthy subjects. Fifteen genes, particular to inflammation, immune response, and cell-to-cell signaling, were differentially expressed in COPD subjects, versus 4 genes in healthy subjects. The authors observed significant differences in subjects' PBMCs, which may elucidate the adverse effects of air pollution particulates on people with COPD.

    View details for DOI 10.1080/01902140802322256

    View details for Web of Science ID 000261737300001

    View details for PubMedID 19085563

  • Real-time PCR for detection of the Aspergillus genus JOURNAL OF ENVIRONMENTAL MONITORING Goebes, M. D., Hildemann, L. M., Kujundzic, E., Hernandez, M. 2007; 9 (6): 599-609

    Abstract

    Aspergillus is a genus of mold that has strong indoor sources, including several species capable of acting as opportunistic pathogens. Previous studies suggest that Aspergillus could serve as an indicator for abnormal mold growth or moisture, making it an important genus for environmental monitoring. Here, a quantitative polymerase chain reaction (qPCR, or real-time PCR) assay is presented for Aspergillus. The assay shows good specificity for the genus, detecting all Aspergillus species tested, although a few non-Aspergillus species are also amplified. Sensitivity testing demonstrates that DNA representing one conidium can be detected. A validation study compared qPCR results against direct microscopy counts using A. fumigatus conidia aerosolized into a laboratory chamber. The assay was then used to quantify Aspergillus in indoor air samples, demonstrating its utility for environmental monitoring. Analysis of a small number of clinical sputum samples showed complete agreement with culturing results.

    View details for DOI 10.1039/b618937g

    View details for Web of Science ID 000247103700031

    View details for PubMedID 17554432

  • Fine organic aerosols collected in a humid, rural location (Great Smoky Mountains, Tennessee, USA): Chemical and temporal characteristics ATMOSPHERIC ENVIRONMENT Yu, L. E., Shulman, M. L., Kopperud, R., Hildemann, L. M. 2005; 39 (33): 6037-6050
  • Size distributions and height variations of airborne particulate matter and cat allergen indoors immediately following dust-disturbing activities JOURNAL OF AEROSOL SCIENCE Montoya, L. D., Hildemann, L. M. 2005; 36 (5-6): 735-749
  • Characterization of organic compounds collected during Southeastern Aerosol and Visibility Study: Water-soluble organic species ENVIRONMENTAL SCIENCE & TECHNOLOGY Yu, L. E., Shulman, M. L., Kopperud, R., Hildemann, L. M. 2005; 39 (3): 707-715

    Abstract

    As part of the Southeastern Aerosol and Visibility Study (SEAVS), water-soluble organic species (WSOS) in fine aerosols collected from July 15 to August 25, 1995, at the Great Smoky Mountain National Park, Tennessee (USA), were chemically classified into seven groups, with concentrations ranging from around 1 to >200 ng/m3. Dicarboxylic acids represented the dominant identified compound class, and succinic acid was the most abundant dicarboxylic acid. The trends in data suggest that most WSOS collected in the SEAVS samples were mainly generated from secondary photochemical reactions, especially during the first (cleaner) half of the sampling campaign. High relative humidity at the sampling site resulted in substantial water uptake by the aerosols, which may have enhanced the levels of succinic acid by reducing its rate of photooxidation. Concurrent trends in malic and malonic acid concentrations suggest these were generated from the oxidation of succinic acid. Consistent with the conversion of 3-hydroxypropanoic acid to malonic acid, it appears that 4-hydroxybutanoic acid served as a major precursor contributing to high levels of succinic acid in the daytime. Nocturnal WSOS generally followed the trend of diurnal WSOS, but they exhibited different chemical compositions and lower concentrations, unlike what has been reported for an urban site. A nocturnal-to-diurnal ratio of succinic acid larger than 0.25 may indicate an atmosphere dominated by photochemical reactions, rather than by primary emissions.

    View details for DOI 10.1021/es0489700

    View details for Web of Science ID 000226712600015

    View details for PubMedID 15757330

  • Outdoor versus indoor contributions to indoor particulate matter (PM) determined by mass balance methods JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION Kopperud, R. J., Ferro, A. R., Hildemann, L. M. 2004; 54 (9): 1188-1196

    Abstract

    This study compares an indoor-outdoor air-exchange mass balance model (IO model) with a chemical mass balance (CMB) model. The models were used to determine the contribution of outdoor sources and indoor resuspension activities to indoor particulate matter (PM) concentrations. Simultaneous indoor and outdoor measurements of PM concentration, chemical composition, and air-exchange rate were made for five consecutive days at a single-family residence using particle counters, nephelometers, and filter samples of integrated PM with an aerodynamic diameter of less than or equal to 2.5 microm (PM2.5) and PM with an aerodynamic diameter of less than or equal to 5 microm (PM5). Chemical compositions were determined by inductively coupled plasma mass-spectrometry. During three high-activity days, prescribed activities, such as cleaning and walking, were conducted over a period of 4-6 hr. For the remaining two days, indoor activities were minimal. Indoor sources accounted for 60-89% of the PM2.5 and more than 90% of the PM5 for the high-activity days. For the minimal-activity days, indoor sources accounted for 27-47% of PM2.5 and 44-60% of the PM5. Good agreement was found between the two mass balance methods. Indoor PM2.5 originating outdoors averaged 53% of outdoor concentrations.

    View details for Web of Science ID 000223701500016

    View details for PubMedID 15468671

  • Elevated personal exposure to particulate matter from human activities in a residence JOURNAL OF EXPOSURE ANALYSIS AND ENVIRONMENTAL EPIDEMIOLOGY Ferro, A. R., Kopperud, R. J., Hildemann, L. M. 2004; 14: S34-S40

    Abstract

    Continuous laser particle counters collocated with time-integrated filter samplers were used to measure personal, indoor, and outdoor particulate matter (PM) concentrations for a variety of prescribed human activities during a 5-day experimental period in a home in Redwood City, CA, USA. The mean daytime personal exposures to PM(2.5) and PM(5) during prescribed activities were 6 and 17 times, respectively, as high as the pre-activity indoor background concentration. Activities that resulted in the highest exposures of PM(2.5), PM(5), and PM(10) were those that disturbed dust reservoirs on furniture and textiles, such as dry dusting, folding clothes and blankets, and making a bed. The vigor of activity and type of flooring were also important factors for dust resuspension. Personal exposures to PM(2.5) and PM(5) were 1.4 and 1.6 times, respectively, as high as the indoor concentration as measured by a stationary monitor. The ratio of personal exposure to the indoor concentration was a function of both particle size and the distance of the human activity from the stationary indoor monitor. The results demonstrate that a wide variety of indoor human resuspension activities increase human exposure to PM and contribute to the "personal cloud" effect.

    View details for DOI 10.1038/sj.jea.7500356

    View details for Web of Science ID 000221128900005

    View details for PubMedID 15118743

  • Source strengths for indoor human activities that resuspend particulate matter ENVIRONMENTAL SCIENCE & TECHNOLOGY Ferro, A. R., Kopperud, R. J., Hildemann, L. M. 2004; 38 (6): 1759-1764

    Abstract

    A mathematical model was applied to continuous indoor and outdoor particulate matter (PM) measurements to estimate source strengths for a variety of prescribed human activities that resuspend house dust in the home. Activities included folding blankets, folding clothes, dry dusting, making a bed, dancing on a rug, dancing on a wood floor, vacuuming, and walking around and sitting on upholstered furniture. Although most of the resuspended particle mass from these activities was larger than 5 microm in diameter, the resuspension of PM2.5 and PM5 was substantial, with source strengths ranging from 0.03 to 0.5 mg min(-1) for PM2.5 and from 0.1 to 1.4 mg min(-1) for PM5. Source strengths for PM > 5 microm could not be quantified due to instrument limitations. The source strengths were found to be a function of the number of persons performing the activity, the vigor of the activity, the type of activity, and the type of flooring.

    View details for DOI 10.1021/es0263893

    View details for Web of Science ID 000220193900025

    View details for PubMedID 15074686

  • Evolution of the mass distribution of resuspended cat allergen (Fel d 1) indoors following a disturbance ATMOSPHERIC ENVIRONMENT Montoya, L. D., Hildemann, L. M. 2001; 35 (5): 859-866
  • Investigations of the proximity effect for pollutants in the indoor environment JOURNAL OF EXPOSURE ANALYSIS AND ENVIRONMENTAL EPIDEMIOLOGY McBride, S. J., Ferro, A. R., Ott, W. R., Switzer, P., Hildemann, L. M. 1999; 9 (6): 602-621

    Abstract

    More than a dozen indoor air quality studies have reported a large discrepancy between concentrations measured by stationary indoor monitors (SIMs) and personal exposure monitors (PEMs). One possible cause of this discrepancy is a source proximity effect, in which pollutant sources close to the respondent cause elevated and highly variable exposures. This paper describes three sets of experiments in a home using real-time measurements to characterize and quantify the proximity effect relative to a fixed distant location analogous to a SIM. In the first set of experiments, using sulfur hexafluoride (SF6) as a continuously emitting tracer pollutant from a point source, measurements of pollutant concentrations were made at different distances from the source under different air exchange rates and source strengths. A second set of experiments used a continuous point source of carbon monoxide (CO) tracer pollutant and an array of high time resolution monitors to collect simultaneous concentration readings at different locations in the room. A third set of experiments measured particle count density and particle-bound polycyclic aromatic hydrocarbon (PAH) concentrations emitted from a continuous particle point source (an incense stick) using two particle counters and two PAH monitors, and included human activity periods both before and during the source emission period. Results from the SF6 and CO experiments show that while the source is emitting, a source proximity effect can be seen in the increases in the mean and median and in the variability of concentrations closest to the source, even at a distance of 2.0 m from the source under certain settings of air exchange rate and source strength. CO concentrations at locations near the source were found to be higher and more variable than the predictions of the mass balance model. For particles emitted from the incense source, a source proximity effect was evident for the fine particle sizes (0.3 to 2.5 microm) and particle-bound PAH up to at least 1.0 m from the source. Analysis of spatial and temporal patterns in the data for the three tracer pollutants reveal marked transient elevations of concentrations as seen by the monitor, referred to as "microplumes," particularly at locations close to the source. Mixing patterns in the room show complex patterns and directional effects, as evidenced by the variable intensity of the microplume activity at different locations. By characterizing the spatial and temporal variability of pollutant concentrations in the home, the proximity effect can be quantified, leading to improved indoor monitoring designs and models of human exposure to air pollutants.

    View details for Web of Science ID 000086103600008

    View details for PubMedID 10638846

  • Characteristics of nitrogen-containing aromatic compounds in coal tars during secondary pyrolysis FUEL Yu, L. E., Hildemann, L. M., Niksa, S. 1999; 78 (3): 377-385
  • Human exposure to particles due to indoor cleaning activities AIR POLLUTION VII Ferro, A., Hildemann, L. M., McBride, S. J., Ott, W., Switzer, P. 1999; 6: 487-496
  • Trends in aromatic ring number distributions of coal tars during secondary pyrolysis ENERGY & FUELS Yu, L. E., Hildemann, L. M., Niksa, S. 1998; 12 (3): 450-456
  • Characterization of coal tar organics via gravity flow column chromatography FUEL Yu, L. E., Hildemann, L. M., Dadamio, J., Niksa, S. 1998; 77 (5): 437-445
  • Sources of fine organic aerosol. 9. Pine, oak and synthetic log combustion in residential fireplaces ENVIRONMENTAL SCIENCE & TECHNOLOGY Rogge, W. F., Hildemann, L. M., Mazurek, M. A., Cass, G. R., SIMONEIT, B. R. 1998; 32 (1): 13-22
  • Modeling vertical spread of airborne pollutants from sources near ground level - Comparison with field measurements JOURNAL OF ENVIRONMENTAL ENGINEERING-ASCE Lin, J. S., Hildemann, L. M. 1997; 123 (12): 1194-1202
  • Water absorption by organics: Survey of laboratory evidence and evaluation of UNIFAC for estimating water activity ENVIRONMENTAL SCIENCE & TECHNOLOGY Saxena, P., Hildemann, L. M. 1997; 31 (11): 3318-3324
  • Sources of fine organic aerosol .7. Hot asphalt roofing tar pot fumes ENVIRONMENTAL SCIENCE & TECHNOLOGY Rogge, W. F., Hildemann, L. M., Mazurek, M. A., Cass, G. R., SIMONEIT, B. R. 1997; 31 (10): 2726-2730
  • Size-resolved quantification of nonviable indoor aeroallergens: A review JOURNAL OF ENVIRONMENTAL ENGINEERING-ASCE Montoya, L. D., Hildemann, L. M. 1997; 123 (10): 965-973
  • Sources of fine organic aerosol .8. Boilers burning No. 2 distillate fuel oil ENVIRONMENTAL SCIENCE & TECHNOLOGY Rogge, W. F., Hildemann, L. M., Mazurek, M. A., Cass, G. R., SIMONEIT, B. R. 1997; 31 (10): 2731-2737
  • Characterization of the Southwestern Desert Aerosol, Meadview, AZ JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION Turpin, B. J., Saxena, P., Allen, G., Koutrakis, P., McMurry, P., Hildemann, L. 1997; 47 (3): 344-356
  • A generalized mathematical scheme to analytically solve the atmospheric diffusion equation with dry deposition ATMOSPHERIC ENVIRONMENT Lin, J. S., Hildemann, L. M. 1997; 31 (1): 59-71
  • Source apportionment of airborne particulate matter using organic compounds as tracers ATMOSPHERIC ENVIRONMENT Schauer, J. J., Rogge, W. F., Hildemann, L. M., Mazurek, M. A., Cass, G. R., SIMONEIT, B. R. 1996; 30 (22): 3837-3855
  • Mathematical modeling of atmospheric fine particle-associated primary organic compound concentrations JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Rogge, W. F., Hildemann, L. M., Mazurek, M. A., Cass, G. R., SIMONEIT, B. R. 1996; 101 (D14): 19379-19394
  • A mathematical model for predicting trends in carbon monoxide emissions and exposures on urban arterial highways JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION Yu, L. E., Hildemann, L. M., Ott, W. R. 1996; 46 (5): 430-440

    Abstract

    The roadway is one of the most important microenvironments for human exposure to carbon monoxide (CO). To evaluate long-term changes in pollutant exposure due to in-transit activities, a mathematical model has been developed to predict average daily vehicular emissions on highways. By utilizing measurements that are specific for a given location and year (e.g., traffic counts, fleet composition), this model can predict emissions for a specific roadway during various time periods of interest, allowing examination of long-term trends in human exposure to CO. For an arterial highway in northern California, this model predicts that CO emissions should have declined by 58% between 1980 and 1991, which agrees fairly well with field measurements of human exposure taken along that roadway during those two years. An additional reduction of up to 60% in CO emissions is predicted to occur between 1991 and 2002, due solely to the continued replacement of older cars with newer, cleaner vehicles.

    View details for Web of Science ID A1996UJ64700005

    View details for PubMedID 8624785

  • Water-soluble organics in atmospheric particles: A critical review of the literature and application of thermodynamics to identify candidate compounds JOURNAL OF ATMOSPHERIC CHEMISTRY Saxena, P., Hildemann, L. M. 1996; 24 (1): 57-109
  • Analytical solutions of the atmospheric diffusion equation with multiple sources and height-dependent wind speed and eddy diffusivities ATMOSPHERIC ENVIRONMENT Lin, J. S., Hildemann, L. M. 1996; 30 (2): 239-254
  • ORGANICS ALTER HYGROSCOPIC BEHAVIOR OF ATMOSPHERIC PARTICLES JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Saxena, P., Hildemann, L. M., McMurry, P. H., Seinfeld, J. H. 1995; 100 (D9): 18755-18770
  • A NONSTEADY-STATE ANALYTICAL MODEL TO PREDICT GASEOUS EMISSIONS OF VOLATILE ORGANIC-COMPOUNDS FROM LANDFILLS JOURNAL OF HAZARDOUS MATERIALS Lin, J. S., Hildemann, L. M. 1995; 40 (3): 271-295
  • SOURCES OF URBAN CONTEMPORARY CARBON AEROSOL ENVIRONMENTAL SCIENCE & TECHNOLOGY Hildemann, L. M., Klinedinst, D. B., Klouda, G. A., Currie, L. A., Cass, G. R. 1994; 28 (9): 1565-1576

    View details for Web of Science ID A1994PE25800011

    View details for PubMedID 22176356

  • Sources of fine organic aerosol. 6. Cigaret smoke in the urban atmosphere. Environmental science & technology Rogge, W. F., Hildemann, L. M., Mazurek, M. A., Cass, G. R., SIMONEIT, B. R. 1994; 28 (7): 1375-1388

    View details for DOI 10.1021/es00056a030

    View details for PubMedID 22176334

  • SEASONAL TRENDS IN LOS-ANGELES AMBIENT ORGANIC AEROSOL OBSERVED BY HIGH-RESOLUTION GAS-CHROMATOGRAPHY AEROSOL SCIENCE AND TECHNOLOGY Hildemann, L. M., Mazurek, M. A., Cass, G. R., SIMONEIT, B. R. 1994; 20 (4): 303-317
  • SOURCES OF FINE ORGANIC AEROSOL .5. NATURAL-GAS HOME APPLIANCES ENVIRONMENTAL SCIENCE & TECHNOLOGY Rogge, W. F., Hildemann, L. M., Mazurek, M. A., Cass, G. R., SIMONEIT, B. R. 1993; 27 (13): 2736-2744
  • SOURCES OF FINE ORGANIC AEROSOL .4. PARTICULATE ABRASION PRODUCTS FROM LEAF SURFACES OF URBAN PLANTS ENVIRONMENTAL SCIENCE & TECHNOLOGY Rogge, W. F., Hildemann, L. M., Mazurek, M. A., Cass, G. R., SIMONEIT, B. R. 1993; 27 (13): 2700-2711
  • LIGNIN PYROLYSIS PRODUCTS, LIGNANS, AND RESIN ACIDS AS SPECIFIC TRACERS OF PLANT CLASSES IN EMISSIONS FROM BIOMASS COMBUSTION ENVIRONMENTAL SCIENCE & TECHNOLOGY SIMONEIT, B. R., Rogge, W. F., Mazurek, M. A., Standley, L. J., Hildemann, L. M., Cass, G. R. 1993; 27 (12): 2533-2541
  • MATHEMATICAL-MODELING OF URBAN ORGANIC AEROSOL - PROPERTIES MEASURED BY HIGH-RESOLUTION GAS-CHROMATOGRAPHY ENVIRONMENTAL SCIENCE & TECHNOLOGY Hildemann, L. M., Cass, G. R., Mazurek, M. A., SIMONELT, B. R. 1993; 27 (10): 2045-2055
  • SOURCES OF FINE ORGANIC AEROSOL .3. ROAD DUST, TIRE DEBRIS, AND ORGANOMETALLIC BRAKE LINING DUST - ROADS AS SOURCES AND SINKS ENVIRONMENTAL SCIENCE & TECHNOLOGY Rogge, W. F., Hildemann, L. M., Mazurek, M. A., Cass, G. R., SIMONEIT, B. R. 1993; 27 (9): 1892-1904
  • SOURCES OF FINE ORGANIC AEROSOL .2. NONCATALYST AND CATALYST-EQUIPPED AUTOMOBILES AND HEAVY-DUTY DIESEL TRUCKS ENVIRONMENTAL SCIENCE & TECHNOLOGY Rogge, W. F., Hildemann, L. M., Mazurek, M. A., Cass, G. R., SIMONEIT, B. R. 1993; 27 (4): 636-651
  • MODELING THE EMISSION AND DISPERSION OF VOLATILE ORGANICS FROM SURFACE AERATION WASTE-WATER TREATMENT FACILITIES WATER RESEARCH Chrysikopoulos, C. V., Hildemann, L. M., Roberts, P. V. 1992; 26 (8): 1045-1052
  • A 3-DIMENSIONAL STEADY-STATE ATMOSPHERIC DISPERSION DEPOSITION MODEL FOR EMISSIONS FROM A GROUND-LEVEL AREA SOURCE ATMOSPHERIC ENVIRONMENT PART A-GENERAL TOPICS Chrysikopoulos, C. V., Hildemann, L. M., Roberts, P. V. 1992; 26 (5): 747-757
  • QUANTITATIVE CHARACTERIZATION OF URBAN SOURCES OF ORGANIC AEROSOL BY HIGH-RESOLUTION GAS-CHROMATOGRAPHY ENVIRONMENTAL SCIENCE & TECHNOLOGY Hildemann, L. M., Mazurek, M. A., Cass, G. R., SIMONEIT, B. R. 1991; 25 (7): 1311-1325
  • SOURCES OF FINE ORGANIC AEROSOL .1. CHARBROILERS AND MEAT COOKING OPERATIONS ENVIRONMENTAL SCIENCE & TECHNOLOGY Rogge, W. F., Hildemann, L. M., Mazurek, M. A., Cass, G. R., SIMONELT, B. R. 1991; 25 (6): 1112-1125

Conference Proceedings


  • Concentration and composition of atmospheric aerosols from the 1995 SEAVS experiment and a review of the closure between chemical and gravimetric measurements Andrews, E., Saxena, P., Musarra, S., Hildemann, L. M., Koutrakis, P., McMurry, P. H., Olmez, I., White, W. H. AIR & WASTE MANAGEMENT ASSOC. 2000: 648-664

    Abstract

    We summarize the results from the various measurements and the inter-sampler comparisons from Southeastern Aerosol and Visibility Study (SEAVS), a study with one of its objectives to test for closure among chemical, gravimetric and optical measurements of atmospheric aerosol particles. Sulfate and organics are the dominant components of the SEAVS fine particles (nominally, particles with aerodynamic diameter < or = 2.5 microns) but between 28 and 42% (range over various samplers) of the gravimetrically measured total fine particle concentration is unidentified by the chemical measurements. Estimates of water associated with inorganic components and measurement imprecision do not totally explain the observed difference between gravimetric and chemical measurements. We examine the theoretical and empirical basis for assumptions commonly made in the published literature to extrapolate total fine particle concentration on the basis of chemical measurements of ions, carbon and elements. We then explore the more general question of closure using the SEAVS data as well as data from other, similar studies reported in the literature. In so combining the SEAVS measurements with other similar studies, we find a strong association between organic carbon and the unidentified component, that is, the fraction of the total fine particle concentration not identified by chemical measurements. We offer several tenable hypotheses for the relationship between the organic and unidentified components that deserve to be tested in future work. Specifically, we hypothesize that (1) errors in the sampling and analysis of organic carbon; (2) estimates of organic mass from measurements of organic carbon; and/or (3) water absorption by organics may all contribute to the observed relationship.

    View details for Web of Science ID 000086986300002

    View details for PubMedID 10842930

  • Contribution of primary aerosol emissions from vegetation-derived sources to fine particle concentrations in Los Angeles Hildemann, L. M., Rogge, W. F., Cass, G. R., Mazurek, M. A., SIMONEIT, B. R. AMER GEOPHYSICAL UNION. 1996: 19541-19549
  • Polarities and ring size distributions of polycyclic aromatic compound emissions during secondary pyrolysis with various coals Yu, L. E., Dadamio, J., Hildemann, L. E., Niksa, S. ELSEVIER SCIENCE BV. 1995: 1939-1942
  • QUANTIFICATION OF URBAN ORGANIC AEROSOLS AT A MOLECULAR-LEVEL - IDENTIFICATION, ABUNDANCE AND SEASONAL-VARIATION Rogge, W. F., Mazurek, M. A., Hildemann, L. M., Cass, G. R., SIMONEIT, B. R. PERGAMON-ELSEVIER SCIENCE LTD. 1993: 1309-1330

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