| Report number: LBNL-750E |
Year: 2008 |
| Title: Secondary organic aerosol from ozone-initiated reactions with terpene-rich household products |
Published in: Atmospheric Environment, Volume 42, Pages 8234–8245. |
| Authors: Coleman, B.K., Lunden, M.M., Destaillats, H., Nazaroff, W.W. |
Type: Journal Article |
| Abstract: We analyzed secondary organic aerosol (SOA) data from a series of small-chamber experiments in which terpene-rich vapors from household products were combined with ozone under conditions analogous to product use indoors. Reagents were introduced into a continuously ventilated 198 L chamber at steady rates. Consistently, at the time of ozone introduction, nucleation occurred exhibiting behavior similar to atmospheric events. The initial nucleation burst and growth was followed by a period in which approximately stable particle levels were
established reflecting a balance between new particle formation, condensational growth, and removal by ventilation. Airborne particles were measured with a scanning mobility particle sizer (SMPS, 10 to 400 nm) in every experiment and with an optical particle counter (OPC, 0.1 to 2.0 µm) in a subset. Parameters for a three-mode lognormal fit to the size distribution at steady state were determined for each experiment. Increasing the supply ozone level increased the steadystate
mass concentration and yield of SOA from each product tested. Decreasing the airexchange rate increased the yield. The steady-state fine-particle mass concentration (PM1.1) ranged from 10 to > 300 µg m-3 and yields ranged from 5% to 37%. Steady-state nucleation rates and SOA mass formation rates were on the order of 10 cm-3 s-1 and 10 µg m-3 min-1, respectively. |
| Report number: LBNL-63240 |
Year: 2008 |
| Title: Ozone consumption and byproduct formation from surface reaction with common materials in aircraft passenger cabins |
Published in: Atmospheric Environment, Volume 42, Pages 642-654. |
| Authors: Coleman, B.K., Destaillats, H., Hodgson, A.T., Nazaroff, W.W. |
Type: Journal Article |
| Abstract: We measured ozone consumption and byproduct formation on materials commonly found in aircraft cabins at flight-relevant conditions. Two series of small-chamber experiments were conducted, with most runs at low relative humidity (10%) and high air-exchange rate (~ 20 h-1). New and used cabin materials (seat fabric, carpet, and plastics) and laundered and worn clothing fabrics (cotton, polyester, and wool) were studied. We first measured ozone deposition to many material samples, and then we measured ozone uptake and primary and secondary emissions of volatile organic compounds (VOCs) from a subset of samples. Deposition velocities ranged from 0.06 to 0.54 cm s-1. Emissions of VOCs were higher with ozone than without ozone in every case. The most commonly emitted compounds were C1 through C10 saturated aldehydes and the squalene oxidation product 6-methyl-5-hepten-2-one. For the compounds measured, summed VOC emission rates in the presence of 55-128 ppb (residual level) ozone ranged from 1.0 to 8.5 µmol h-1 m-2. Total byproduct yield ranged from 0.07 to 0.24 moles of product volatilized per mole of ozone consumed. Results were used to estimate the relative contribution of different materials to ozone deposition and byproduct emissions in a typical aircraft cabin. The dominant contributor to both was clothing fabrics, followed by seat fabric. Results indicate that ozone reactions with surfaces substantially reduce the ozone concentration in the cabin but also generate volatile byproducts. |
| Report number: LBNL-63241 |
Year: 2007 |
| Title: Ozone-initiated chemistry in an occupied simulated aircraft cabin |
Published in: Environmental Science and Technology, Volume 41, Pages 6177-6184. |
| Authors: Weschler, C.J., Wisthaler, A., Cowlin, S., Tamas, G., Strom-Tejsen, P., Hodgson, A.T., Destaillats, H., Herrington, J., Zhang, J., Nazaroff, W.W. |
Type: Journal Article |
| Abstract: We have used multiple analytical methods to characterize the gas-phase products formed when ozone was added to cabin air during simulated 4-hour flights that were conducted in a reconstructed section of a B-767 aircraft containing human occupants. Two separate groups of 16 females were each exposed to four conditions: low air exchange (4.4 h-1), < 2 ppb ozone; low air exchange, 61-64 ppb ozone; high air exchange (8.8 h-1), < 2 ppb ozone; and high air exchange, 73-77 ppb ozone. The addition of ozone to the cabin air increased the levels of identified byproducts from ~ 70 to 130 ppb at the lower air exchange rate and from ~ 30 to 70 ppb at the higher air exchange rate. Most of the increase was attributable to acetone, nonanal, decanal, 4-oxopentanal (4-OPA), 6-methyl-5-hepten-2-one (6-MHO), formic acid and acetic acid, with 0.25 to 0.30 moles of quantified product volatilized per mole of ozone consumed. Several of these compounds reached levels above their reported odor thresholds. Most byproducts were derived from surface reactions with occupants and their clothing, consistent with the inference that occupants were responsible for the removal of > 55% of the ozone in the cabin. The observations made in this study have implications for other indoor settings. Whenever human beings and ozone are simultaneously present, one anticipates production of acetone, nonanal, decanal, 6-MHO, geranyl acetone and 4-OPA. |
| Report number: LBNL-63229 |
Year: 2007 |
| Title: Quinone emissions from gasoline and diesel motor vehicles |
Published in: Environmental Science and Technology, Volume 41, Pages 4548-4554. |
| Authors: Jakober, C.A., Riddle, S.G., Robert, M.A., Destaillats, H., Charles, M.J., Green, P.G., Kleeman, M.J. |
Type: Journal Article |
| Abstract: Gas- and particle-phase emissions from gasoline and diesel vehicles operated on chassis dynamometers were collected using annular denuders, quartz filters, and PUF substrates. Quinone species were measured using 0-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine derivatization in conjunction with gas chromatography-mass spectrometry and highperformance liquid chromatography-mass spectrometry. Nine quinones were observed, ranging from C6 to C16. New
species identified in motor vehicle exhaust include methyl-1,4-benzoquinone, 2-methyl-1,4-naphthoquinone (MNQN), and aceanthrenequinone. Gas-phase motor vehicle emissions of quinones are also reported for the first time. Six gasphase
quinones were quantified with emission rates of 2-28 000 µg L-1 fuel consumed. The most abundant gas-phase quinones were 1,4-benzoquinone (BQN) and
MNQN. The gas-phase fraction was ≥69% of quinone mass for light-duty gasoline emissions, and ≥84% for heavy duty diesel emissions. Eight particle-phase quinones
were observed between 2 and 1600 µg L-1, with BQN the most abundant species followed by 9,10-phenanthrenequinone and 1,2-naphthoquinone. Current particle-phase quinone measurements agree well with the few available previous results. Further research is needed concerning the gas-particle partitioning behavior of quinones in ambient and combustion source conditions. |
| Report number: LBNL-1274E |
Year: 2007 |
| Title: Thermophoresis and its thermal parameters for aerosol collection |
Published in: U.S. Department of Energy Journal of Undergraduate Research, Volume 7, Pages 37-42. |
| Authors: Huang, Z., Apte, M.G., Gundel, L.A |
Type: Journal Article |
| Abstract: The particle collection effi ciency of a prototype environmental tobacco smoke (ETS) sampler based on the use of thermophoresis is determined by optimizing the operational voltage that determines its thermal gradient. This sampler’s heating element was made of three sets of thermophoretic (TP) wires 25µm in diameter suspended across a channel cut in a printed circuit board and mounted with collection surfaces on both sides. The separation between the heating element and the room temperature collection surface was determined in a numerical simulation based on the Brock-Talbot model. Other thermal parameters of this TP ETS sampler were predicted by the Brock-Talbot model for TP deposition. From the normalized results the optimal collection ratio was expressed in terms of operational voltage and fi lter mass. Prior to the Brock-Talbot model simulation for this sampler, 1.0V was used arbitrarily. The operational voltage was raised to 3.0V, and the collection effi ciency was increased by a factor of fi ve for both theory and experiment. |
| Report number: LBNL-57273 |
Year: 2006 |
| Title: On The Importance of Organic Oxygen for Understanding Organic Aerosol Particles |
Published in: Journal of Aerosol Science and Technology, Volume 40, Pages 128-133. |
| Authors: Pang, Y., Turpin, B.J., Gundel, L A. |
Type: Journal Article |
| Abstract: This study shows how aerosol organic oxygen data could provide new and independent information about organic aerosol mass, aqueous solubility of organic aerosols, formation of secondary organic aerosol (SOA) and the relative contributions of anthropogenic and biogenic sources. For more than two decades atmospheric aerosol organic mass concentration has usually been estimated by multiplying the measured carbon content by an assumed organic mass (OM)-to-organic carbon (OC ) factor of 1.4. However, this factor can vary from 1.0 to 2.5 depending on location. This great uncertainty about aerosol organic mass limits our understanding of the influence of organic aerosol on climate, visibility and health.
New examination of organic aerosol speciation data shows that the oxygen content is the key factor responsible for the observed range in the OM-to-OC factor. When organic oxygen content is excluded, the ratio of non-oxygen organic mass to carbon mass varies very little across different environments (1.12 to 1.14). The non-oxygen-OM-to-non-oxygen OC factor for all studied sites (urban and non-urban) is 1.13± 0.02. The uncertainty becomes an order of magnitude smaller than the uncertainty in the best current estimates of organic mass to organic carbon ratios (1.6± 0.2 for urban and 2.1± 0.2 for non-urban areas). When aerosol organic oxygen data become available, organic aerosol mass can be quite accurately estimated using just OC and organic oxygen (OO) without the need to know whether the aerosol is fresh or aged. In addition, aerosol organic oxygen data will aid prediction of water solubility since compounds with OO-to-OC higher than 0.4 have water solubilities higher than 1g per 100 g water. |
| Report number: LBNL-54843 |
Year: 2005 |
| Title: Particle Deposition in Ventilation Ducts: Connectors, Bends and Developing Flow |
Published in: Aerosol Science and Technology, Volume 39, Pages 139-150. |
| Authors: Sippola, M.R., Nazaroff, W.W. |
Type: Journal Article |
| Abstract: In ventilation duct flow the turbulent flow profile is commonly disturbed or not fully developed and these conditions are likely to influence particle deposition to duct surfaces. Particle deposition rates at eight S-connectors, in two 90° duct bends and in two ducts where the turbulent flow profile was not fully developed were measured in a laboratory duct system with both galvanized steel and internally insulated ducts with hydraulic diameters of 15.2 cm. In the steel duct system, experiments with nominal particle diameters of 1, 3, 5, 9 and 16 µm were conducted at each of three nominal air speeds: 2.2, 5.3 and 9.0 m/s. In the insulated duct system, deposition of particles with nominal diameters of 1, 3, 5, 8 and 13 µm was measured at nominal air speeds of 2.2, 5.3 and 8.8 m/s. Fluorescent techniques were used to directly measure the deposition velocities of monodisperse fluorescent particles to duct surfaces.
Deposition at S-connectors, in bends and in straight ducts with developing turbulence was often greater than deposition in straight ducts with fully developed turbulence for equal particle sizes, air speeds and duct surface orientations. Deposition rates at all locations were found to increase with an increase in particle size or air speed. High deposition rates at S-connectors resulted from impaction and these rates were nearly independent of the orientation of the S-connector. Deposition rates in the two 90° bends differed by more than an order of magnitude in some cases, probably because of the difference in turbulence conditions at the bend inlets. In straight steel ducts where the turbulent flow profile was developing, the deposition enhancement relative to fully developed turbulence generally increased with air speed and decreased with downstream distance from the duct inlet. This enhancement was greater at the duct ceiling and wall than at the duct floor. In insulated ducts, deposition enhancement was less pronounced overall than in steel ducts. Trends that were observed in steel ducts were present, but weaker, in insulated ducts. |
| Report number: LBNL-53480 |
Year: 2005 |
| Title: Assessing uncertainties in the relationship between inhaled particle concentration, internal deposition and health effects, Chapter 9 |
Published in: Aerosols Handbook: Measurement, Dosimetry and Health Effects, Pages 157-188. |
| Authors: Price, P. N., Ruzer, L.S., Hurley, N.H. |
Type: Book Section |
| Abstract: The question that ultimately motivates most aerosol inhalation research is: for a given inhaled atmosphere, what health effects will result in a specified population? To attempt to address this question, quantitative research on inhaled aerosols has been performed for at least fifty years (Landahl et al, 1951). The physical factors that determine particle deposition have been determined, lung morphology has been quantified (particularly for adults), models of total particle deposition have been created and validated, and a large variety of inhalation experiments have been performed. However many basic questions remain, some of which are identified by the U.S. Committee on Research Priorities for Airborne Particulate Matter (NRC 1998a) as high-priority research areas. Among these are: What are the quantitative relationships between outdoor concentrations measured at stationary monitoring stations, and actual personal exposures? What are the exposures to biologically important constituents of particulate matter that cause responses in potentially susceptible subpopulations and the general population? What is the role of physicochemical characteristics of particulate matter in causing adverse health effects? As these questions show, in spite of significant progress in all areas of aerosol research, many of the most important practical questions remain unanswered or inadequately answered.
In this chapter, we discuss the sources and magnitudes of error that hinder the ability to answer basic questions concerning the health effects of inhaled aerosols. We first consider the phenomena that affect the epidemiological studies, starting with studies of residential radon and moving on to fine particle air pollution. Next we discuss the major uncertainties in physical and physiological modeling of the causal chain that leads from inhaled aerosol concentration, to deposition in the airway, to time-dependent dose (that is, the concentration of particles at a given point in the lungs as function of time), to physiological effects, and finally to health effect. |
| Report number: LBNL-51631 |
Year: 2003 |
| Title: A concentration rebound method for measuring particle penetration and deposition in the indoor environment |
Published in: Aerosol Science & Technology, Volume 37, Pages 847-864. |
| Authors: Thatcher, Tracy L., Lunden, Melissa M., Revzan, Kenneth L., Sextro, Richard G., Brown, Nancy J. |
Type: Journal Article |
| Abstract: Continuous, size resolved particle measurements were performed in two houses in order to determine size- dependent particle penetration into and deposition in the indoor environment. The experiments consisted of three parts: (1) measurement of the particle loss rate following artificial elevation of indoor particle concentrations, (2) rapid reduction in particle concentration through induced ventilation by pressurization of the houses with HEPA-filtered air, and (3) measurement of the particle concentration rebound after house pressurization stopped. During the particle concentration decay period, when indoor concentrations are very high, losses due to deposition are large compared to gains due to particle infiltration. During the concentration rebound period, the opposite is true. The large variation in indoor concentration allows the effects of penetration and deposition losses to be separated by the transient, two-parameter model we employed to analyze the data. For the two houses studied, we found that as particles increased in diameter from 0.1 to 10 µm, penetration factors ranged from ~1 to 0.3 and deposition loss rates ranged from 0.1 and 5 h-1. The decline in penetration factor with increasing particle size was less pronounced in the house with the larger normalized leakage area. |
| Report number: LBNL-52449 |
Year: 2003 |
| Title: Modeling particle loss in ventilation ducts |
Published in: Atmospheric Environment, Volume 37, Pages 5597-5610. |
| Authors: Sippola, M.R., Nazaroff, W.W. |
Type: Journal Article |
| Abstract: Empirical equations were developed and applied to predict losses of 0.01-100 µm airborne particles making a single pass through 120 different ventilation duct runs typical of those found in mid-sized office buildings. For all duct runs, losses were negligible for submicron particles and nearly complete for particles larger than 50 µm. The 50th percentile cut-point diameters were 15 µm in supply runs and 25 µm in return runs. Losses in supply duct runs were higher than in return duct runs, mostly because internal insulation was present in portions of supply duct runs, but absent from return duct runs. Single-pass equations for particle loss in duct runs were combined with models for predicting ventilation system filtration efficiency and particle deposition to indoor surfaces to evaluate the fates of particles of indoor and outdoor origin in an archetypal mechanically ventilated building. Results suggest that duct losses are a minor influence for determining indoor concentrations for most particle sizes. Losses in ducts were of a comparable magnitude to indoor surface losses for most particle sizes. For outdoor air drawn into an unfiltered ventilation system, most particles smaller than 1 mm are exhausted from the building. Large particles deposit within the building, mostly in supply ducts or on indoor surfaces. When filters are present, most particles are either filtered or exhausted. The fates of particles generated indoors follow similar trends as outdoor particles drawn into the building. |
| Report number: LBNL-53585 |
Year: 2003 |
| Title: Experiments Measuring Particle Deposition from Fully Developed Turbulent Flow in Ventilation Ducts |
Published in: Aerosol Science and Technology, Volume 38, Pages 914-925. |
| Authors: Sippola, M.R., Nazaroff, W.W. |
Type: Journal Article |
| Abstract: Particle deposition in ventilation ducts influences particle exposures of building occupants and may lead to a variety of indoor air quality concerns. Experiments have been performed in a laboratory to study the effects of particle size and air speed on deposition rates of particles from turbulent air flows in galvanized steel and internally insulated ducts with hydraulic diameters of 15.2 cm. The duct systems were constructed of materials typically found in commercial heating, entilating and air conditioning (HVAC) systems. In the steel duct system, experiments with nominal particle sizes of 1, 3, 5, 9 and 16 µm were conducted at each of three nominal air speeds: 2.2, 5.3 and 9.0 m/s. In the insulated duct system, deposition rates of particles with nominal sizes of 1, 3, 5, 8 and 13 µm were measured at nominal air speeds of 2.2, 5.3 and 8.8 m/s. Fluorescent techniques were used to directly measure the deposition velocities of monodisperse fluorescent particles to duct surfaces (floor, wall and ceiling) at two straight duct sections where the turbulent flow profile was fully developed. In steel ducts, deposition rates were higher to the duct floor than to the wall, which were, in turn, greater than to the ceiling. In insulated ducts, deposition was nearly the same to the duct floor, wall and ceiling for a given particle size and air speed. Deposition to duct walls and ceilings was greatly enhanced in insulated ducts compared to steel ducts. Deposition velocities to each of the three duct surface orientations in both systems were found to increase with increasing particle size or air velocity over the ranges studied. Deposition rates measured in the current experiments were in general agreement with the limited observations of similar systems by previous researchers. |
| Report number: LBNL-53586 |
Year: 2003 |
| Title: Associations between classroom CO2 concentrations and student attendance |
Published in: |
| Authors: Shendell, D.G., Prill, R., Fisk, W.J., Apte, M.G., Blake, D., Faulkner, D. |
Type: Report |
| Abstract: Student attendance in American public schools is a critical factor in securing limited operational funding. Student and teacher attendance influence academic performance. Limited data exist on indoor air and environmental quality (IEQ) in schools, and how IEQ affects attendance, health, or performance. This study explored the association of student absence with measures of indoor minus outdoor carbon dioxide concentration (dCO2). Absence and dCO2 data were collected from 409 traditional and 25 portable classrooms from 14 schools located in six school districts in the states of Washington and Idaho. Study classrooms had individual heating, ventilation, and air conditioning (HVAC) systems, except two classrooms without mechanical ventilation. Classroom attributes, student attendance and school-level ethnicity, gender, and socioeconomic status (SES) were included in multivariate modeling. Forty-five percent of classrooms studied had short-term indoor CO2 concentrations above 1000 parts-per-million (ppm). A 1000 ppm increase in dCO2 was associated (p< 0.05) with a 0.5% to 0.9% decrease in annual average daily attendance (ADA), corresponding to a relative 10% to 20% increase in student absence. Outside air (ventilation) rates estimated from dCO2 and other collected data were not associated with absence. Annual ADA was 2% higher (p < 0.0001) in traditional than in portable classrooms. |
| Report number: LBNL-52221 |
Year: 2003 |
| Title: Use of time- and chemically resolved particulate data to characterize the infiltration of outdoor PM2.5 into a residence in the San Joaquin Valley |
Published in: Environmental Science and Technology, Volume 37, Pages 4724-4732. |
| Authors: Lunden, M.M., Thatcher, T.L., Hering, S.V., Brown, N.J. |
Type: Journal Article |
| Abstract: No abstract available. |
| Report number: LBNL-52795 |
Year: 2003 |
| Title: The Transformation of Outdoor Ammonium Nitrate Aerosols in the Indoor Environment |
Published in: Atmospheric Environment, Volume 37, Pages 5633-5644. |
| Authors: Lunden, M.M., Revzan, K. L., Fisher, M.L., Thatcher, T.L., Littlejohn, D., Hering, S.V., Brown, N.J. |
Type: Journal Article |
| Abstract: No abstract available |
| Report number: LBNL-53212 |
Year: 2003 |
| Title: Performance and Costs of Particle Air Filtration in HVAC Supply Airstreams |
Published in: HPAC Engineering, Volume 75, Pages 24-36. |
| Authors: Fisk, W.J., Faulkner, D., Palonen, J., Seppänen, O. |
Type: Journal Article |
| Abstract: This paper uses a model, and data on particle size distributions, filter efficiencies, and particle deposition rates to estimate the reductions in the indoor mass concentrations of particles attainable from use of filters in HVAC supply airstreams. Additionally, the energy and total costs of the filtration options are estimated. Predicted reductions in cat and dust-mite allergen concentrations range from 20% to 60%. Increasing filter efficiencies above approximately ASHRAE Dust Spot 65% (MERV 11) does not significantly reduce predicted indoor concentrations of these allergens. For environmental tobacco smoke particles and outdoor fine mode particles, calculations indicate that relatively large, e.g., 80%, decreases in indoor concentrations are attainable with practical filter efficiencies. Increasing the filter efficiency above ASHRAE Dust Spot 85% (MERV 13) results in only modest incremental decreases in concentrations. Energy costs and total costs do not always increase for higher efficiency filters. Total estimated filtration costs of $0.70 to $1.80 per person per month are insignificant relative to salaries, rent, or health insurance costs. |
| Report number: LBNL-50160 |
Year: 2002 |
| Title: The effect of penetration factor, deposition, and environmental factors on the indoor concentration of pm2.5 sulfate, nitrate, and carbon |
Published in: Proceedings of the Indoor Air 2002 Conference, Monterey, CA, Volume 1, Pages 846-851. |
| Authors: Thatcher, T.L., Lunden, M.M., Sextro, R.G., Hering, S., Brown, N.J. |
Type: Conference Proceedings |
| Abstract: Indoor exposure to particles of outdoor origin constitutes an important exposure pathway. We conducted an intensive set of indoor particle measurements in an unoccupied house under differing operating conditions. Real-time measurements were conducted both indoors and outdoors, including PM2.5 nitrate, sulfate, and carbon. Because the time-scale of the fluctuations in outdoor particle concentrations and meteorological conditions are often similar to the time constant for building air exchange, a steady state concentration may never be reached. The time-series experimental data were used to determine the effect of changes in air exchange rate and indoor/outdoor temperature and relative humidity differences on indoor particle concentrations. A multivariate regression was performed to investigate the difference between measured indoor concentrations and results from a simple time-dependent physical model. Environmental conditions had a significant effect on indoor concentrations of all three PM2.5 species, but did not explain all of the model variation. |
| Report number: LBNL-48414 |
Year: 2002 |
| Title: Effects of Room Furnishings and Air Speed on Particle Deposition Rates Indoors |
Published in: Atmospheric Environment, Volume 36, Pages 1811-1819. |
| Authors: Thatcher, T.L., Lai, A.C.K., Moreno-Jackson, R., Sextro, R.G., Nazaroff, W.W. |
Type: Journal Article |
| Abstract: No Abstract available |
| Report number: |
Year: 2002 |
| Title: Modeling Particle Deposition In Ventilation Ducts |
Published in: Proceedings of the Indoor Air 2002 Conference, Monterey, CA, Volume 1, Pages 515-520. |
| Authors: Sippola, M.R., Nazaroff, W.W. |
Type: Conference Proceedings |
| Abstract: This paper describes predictions from two models of fractional particle loss in four typical HVAC duct runs. One model is a state-of-the-art Eulerian formulation; the second is based on empirical fits to experimental particle deposition data collected in a laboratory. The experiments are briefly described and sample results are presented. The Eulerian model only predicts deposition from fully developed turbulence, while the empirical model can be applied to duct bends and developing turbulence as well. The models predict almost no losses for particles smaller than 1 µm and nearly complete loss of particles larger than 40 µm in all duct runs. The empirical model suggests that particle loss in ventilation ducts is dominated by gravitational settling to the floor of horizontal ducts, and by deposition to zones where turbulent flow is undeveloped, such as in bends and in duct sections immediately after bends. |
| Report number: LBNL-49339 |
Year: 2002 |
| Title: Modeling Particle Deposition on HVAC Heat Exchangers |
Published in: Proceedings of the Indoor Air 2002 Conference, Monterey, CA, Volume 1, Pages 521-526. |
| Authors: Siegel, J.A., Nazaroff, W.W. |
Type: Conference Proceedings |
| Abstract: Fouling of fin-and-tube heat exchangers by particle deposition leads to diminished effectiveness in supplying ventilation and air conditioning. This paper explores mechanisms that cause particle deposition on heat exchanger surfaces. We present a model that accounts for impaction, diffusion, gravitational settling, and turbulence. Simulation results suggest that some submicron particles deposit in the heat exchanger core, but do not cause significant performance impacts. Particles between 1 and 10 µm deposit with probabilities ranging from 1 -- 20 % with fin edge impaction representing the dominant mechanism. Particles larger than 10 µm deposit by impaction on refrigerant tubes, gravitational settling on fin corrugations, and mechanisms associated with turbulent airflow. The model results agree reasonably well with experimental data, but the deposition of larger particles at high velocities is underpredicted. Geometric factors, such as discontinuities in the fins, are hypothesized to be responsible for the discrepancy. |
| Report number: LBNL-47437 |
Year: 2002 |
| Title: Indoor particulate matter of outdoor origin: importance of size-dependent removal mechanisms |
Published in: Environmental Science & Technology, Volume 36, Pages 200-207. |
| Authors: Riley, W.J., T.E. McKone, A.C.K. Lai, W.W. Nazaroff |
Type: Journal Article |
| Abstract: Adverse human health effects have been observed to correlate with levels of outdoor particulate matter (PM), even though most human exposure to PM of outdoor origin occurs indoors. In this study, we apply a model and empirical data to explore the indoor PM levels of outdoor origin for two major building types: offices and residences. Typical ventilation rates for each building type are obtained from the literature. Published data are combined with theoretical analyses to develop representative particle penetration coefficients, deposition loss rates, and ventilation-system filter efficiencies for a broad particle size range (i.e., 0.001-10 um). We apply archetypal outdoor number, surface area, and mass PM size distributions for both urban and rural airsheds. We also use data on mass-weighted size distributions for specific chemical constituents of PM: sulfate and elemental carbon. Predictions of the size-resolved indoor proportion of outdoor particles (IPOP) for various conditions and ambient particle distributions are then computed. The IPOP depends strongly on the ambient particle size distribution, building type and operational parameters, and PM metric. We conclude that an accurate determination of exposure to particles of ambient origin requires explicit consideration of how removal processes in buildings vary with particle size. |
| Report number: LBNL-49730 |
Year: 2002 |
| Title: Theoretical study of pollutant mixing in rooms induced by occupancy |
Published in: Proceedings of the Room Vent 2002 Conference, Copenhagen, Denmark, Pages 257-260. |
| Authors: Mora, L., A.J. Gadgil |
Type: Conference Proceedings |
| Abstract: Airflow and pollutant transport models are commonly based on the approximation that air is instantaneously well mixed in a zone. In many circumstances this approximation is unsatisfactory. We present a semi-empirical model to predict the time required by a pollutant to disperse in a room, owing to the effects of room occupancy (room mixing induced by thermal plumes, stirring by people walking about and breathing). We base our estimates on previous experimental work correlating the mixing tome for a pollutamt pulse released in a room to the mechanical energy supplied to the room air. Our results suggests that people moving about in a room can induce rapid mixing. For example, the mixing timeresulting from a person walking at 1.4 m/s in a 30 m^3 room is predicted to be about 4 minutes . In this case, the assumption that air is well mixed could be reasonable. |
| Report number: LBNL-50158 |
Year: 2002 |
| Title: The Transformation Of Outdoor Ammonium Nitrate Aerosols In The Indoor Environment |
Published in: Proceedings of the Indoor Air 2002 Conference, Monterey, CA, Volume 5, Pages 74-79. |
| Authors: Lunden, M.M., Thatcher, T.L., Littlejohn, D., Fischer, M.L., Hering, S.V., Sextro, R.G., Brown, N.J. |
Type: Conference Proceedings |
| Abstract: Recent studies associate particulate air pollution with adverse health effects; however, the exposure to indoor particles of outdoor origin is not well characterized, particularly for individual chemical species. In response to this, a field study in an unoccupied, single-story residence in Clovis, California has been conducted. Real-time particle monitors were used both outdoors and indoors to quantify PM2.5 nitrate, sulfate, and carbon. The results show that reduced indoor sulfate and carbon levels are primarily due to deposition and penetration losses. However, measured indoor ammonium nitrate levels were often observed to be at significantly lower levels than expected based solely on penetration and deposition losses. The additional reduction appears to be due to the transformation of ammonium nitrate into ammonia and nitric acid indoors, which are subsequently lost by deposition and sorption to indoor surfaces. The size of the effect is dependent upon factors such as temperature, relative humidity, and ventilation rate. |
| Report number: No LBNL number |
Year: 2002 |
| Title: Particle Penetration Through Windows |
Published in: Proceedings of the Indoor Air 2002 Conference, Monterey, CA, Volume 1, Pages 862-867. |
| Authors: Liu, D.L., Nazaroff, W.W. |
Type: Conference Proceedings |
| Abstract: This study aims to characterize the fractional penetration of airborne particles through windows, one of the important sites of air leakage through building envelopes. Two aluminum windows were evaluated, one with weatherstripping and one without. For each experiment, a finished window was mounted and sealed in a plywood panel that separated two well-mixed compartments. A small pressure difference was established between the compartments to induce a constant rate of airflow through leakage paths in the window. Particles were injected into one chamber and their concentrations were measured in both chambers. Two methods were employed to evaluate the size-resolved particle penetration: a steady-state method and a dynamic, concentration growth method. The results indicate that airborne particles of 0.2 to 3 ?m penetrate through both test windows fairly effectively, while significant particle losses are observed for particles smaller and larger than this range. |
| Report number: LBNL-49980 |
Year: 2002 |
| Title: Indoor, Outdoor And Regional Profiles Of Pm2.5 Sulfate, Nitrate And Carbon |
Published in: Proceedings of the Indoor Air 2002 Conference, Monterey, CA, Volume 1, Pages 874-879. |
| Authors: Hering, S.V., Lunden, M.M., Kirchstetter, T.W., Thatcher, T.L., Revzan, K.L., Sextro, R.G., Brown, N.J., Watson, J., Chow, J. |
Type: Conference Proceedings |
| Abstract: Fine particle concentrations were measured simultaneously at three locations: a regional monitoring site in Fresno, California, a backyard of an unoccupied residence in Clovis, California located 6 km northeast of the regional site; and indoors at the same residence. Measurements included 10-min determination of PM2.5 nitrate, sulfate and carbon using an automated collection and vaporization system, and black carbon measured by light attenuation through a filter deposit. Specific outdoor PM2.5 constituents were compared to assess the appropriateness of using regional data to model indoor concentrations from outdoor sources. The outdoor data show that, in general, the regional results provide a good representation of the concentrations seen at the building exterior. The indoor concentrations showed considerable attenuation as well as a broadening and time-lag for the concentration peaks. The concentration reduction was the largest for PM2.5 nitrate, which appears to undergo phase changes in addition to indoor deposition and penetration losses. |
| Report number: LBNL-47833 |
Year: 2002 |
| Title: Performance and cost of particle air filtration technologies |
Published in: Indoor Air, Volume 12, Pages 223-234. |
| Authors: Fisk, WJ, Faulkner, D, Palonen, J, Seppänen, O |
Type: Journal Article |
| Abstract: This paper predicts the reductions in the indoor mass concentrations of particles attainable from use of filters in building supply airstreams and also from use of stand-alone fan-filter units. Filters with a wide efficiency range are considered. Predicted concentration reductions are provided for indoor-generated particles containing dust mite and cat allergen, for environmental tobacco smoke particles, and for outdoor- air fine mode particles. Additionally, this paper uses a simple model and available data to estimate the energy and total costs of the filtration options. Predicted reductions in cat and dust-mite allergen concentrations range from 20% to 80%. To obtain substantial, e.g., 50%, reductions in indoor concentrations of these allergens, the rate of airflow through the filter must be at least a few indoor volumes per hour. Increasing filter efficiencies above approximately ASHRAE Dust Spot 65% does not significantly reduce predicted indoor concentrations of these allergens. For environmental tobacco smoke particles and outdoor fine mode particles, calculations indicate that relatively large, e.g., 80%, decreases in indoor concentrations are attainable with practical filter efficiencies and flow rates. Increasing the filter efficiency above ASHRAE 85% results in only modest predicted incremental decreases in indoor concentration. Energy costs and total costs can be similar for filtration using filters with a wide range of efficiency ratings. Total estimated filtration costs of approximately $0.70 to $1.80 per person per month are insignificant relative to salaries, rent, or health insurance costs. |
| Report number: LBNL-49615 |
Year: 2002 |
| Title: Predicting Indoor PM2.5 Of Outdoor Origin: Testing a transient size-resolved Model Using Intensive Measurements From A Residence |
Published in: Proceedings of the Indoor Air 2002 Conference, Monterey, CA, Volume 1, Pages 152-157. |
| Authors: Fischer, M.L., Lunden, M.M., Thatcher, T.L., Sextro, R.G., Brown, N.J. |
Type: Conference Proceedings |
| Abstract: We report tests of a model for indoor PM2.5 of outdoor origin that incorporates physical mechanisms for time dependent transport, and size dependent penetration and deposition. This work was performed using information obtained from an intensive study of a house near Fresno, CA, USA. During the multi-week study covering two seasons, we measured particles in both indoor and outdoor air, with high temporal, chemical, and size resolution, and other variables that also affect transport and fate. Results suggest that 1) the model captures a significant fraction of the variation in meteorologically forced air infiltration rate, 2) the predicted indoor/outdoor PM2.5 ratio is not consistent with the measured ratio unless a large (unphysical) deposition rate > 2 hr-1 is assumed, and 3) the differences between model and measurement in indoor PM2.5 are likely due to loss of volatile ammonium-nitrate aerosol. We conclude that nitrate particle volitization must be included in the model formulation. |
| Report number: LBNL-51001 |
Year: 2002 |
| Title: Building a predictive model of indoor concentrations of outdoor PM-2.5 for a residential research house in Clovis, California |
Published in: |
| Authors: Fischer, M.L., Lunden, M.M., Thatcher, T.L., Littlejohn, D., Kirchstetter, T.W., Hering, S.V., Sextro, R.G., Brown, N.J. |
Type: Report |
| Abstract: The prevalence of relocatable classrooms (RCs) at schools is rising due to federal and state initiatives to reduce K-3 class size, and limited capital resources. Concerns regarding inadequate ventilation and indoor air and environmental quality (IEQ) in RCs have been raised. Adequate ventilation is an important link between improved IEQ and energy efficiency for schools. Since students and teachers spend the majority of a 7-8 hour school day inside classrooms, indoor contaminant concentrations are assumed to drive personal school-day exposures. We conducted a demonstration project in new relocatable classrooms (RCs) during the 2001-02 school year to address these issues. Four new 24' x 40' (960 ft2) RCs were constructed and sited in pairs at an elementary school campus in each of two participant school districts (SD) in Northern California. Each RC was equipped with two heating, ventilation, and air conditioning (HVAC) systems, one per module. The two HVAC systems were a standard heat pump with intermittent 25-50% outdoor air ventilation and an energy-efficient advanced system, based on indirect-direct evaporative cooling with an integrated natural gas-fired hydronic heating loop and improved particle filtration, providing continuous 100% outdoor air ventilation at = 15 ft3 min-1 occupant-1. Alternate carpets, wall panels, and ceiling panels were installed in two classrooms -- one in each pair -- based on the results of a laboratory study of VOC emissions from standard and alternate materials. Numerous IEQ and outdoor air quality and meteorological parameters were measured either continuously over the school year or as integrated school day samples during the fall cooling and winter heating seasons. Details of the RC designs, the field monitoring methodology including handling, storage, transport and management of chemical samples and data, and analyses to be conducted are presented. |
| Report number: LBNL-49321 |
Year: 2001 |
| Title: Factors Affecting the Concentration of Outdoor Particles Indoors (COPI): Identification of Data Needs and Existing Data |
Published in: |
| Authors: Thatcher, T.L., McKone, T. E., Fisk, W. J., Sohn, M.D., Delp, W.W., Riley, W.J., Sextro, R. G. |
Type: Report |
| Report number: LBNL-47669 |
Year: 2001 |
| Title: Deposition of biological aerosols on HVAC heat exchangers |
Published in: |
| Authors: Siegel, J.A., Walker, I.S. |
Type: Report |
| Abstract: Many biologically active materials are transported as bioaerosols 1-10 µm in diameter. These particles can deposit on cooling and heating coils and lead to serious indoor air quality problems. This paper investigates several of the mechanisms that lead to aerosol deposition on fin and tube heat exchangers. A model has been developed that incorporates the effects of several deposition mechanisms, including impaction, Brownian and turbulent diffusion, turbophoresis, thermophoresis, diffusiophoresis, and gravitational settling. The model is applied to a typical range of air velocities that are found in commercial and residential HVAC systems 1 -- 6 m/s (200 -- 1200 ft/min), particle diameters from 1 -- 8 µm, and fin spacings from 3.2 -- 7.9 fins/cm (8 -- 16 fins/inch or FPI). The results from the model are compared to results from an experimental apparatus that directly measures deposition on a 4.7 fins/cm (12 FPI) coil. The model agrees reasonably well with this measured data and suggests that cooling coils are an important sink for biological aerosols and consequently a potential source of indoor air quality problems. |
| Report number: LBNL-48929 |
Year: 2001 |
| Title: Building a predictive model of indoor concentrations of outdoor PM-2.5 in homes |
Published in: |
| Authors: Lunden, M.M., Thatcher, T.L., Littlejohn, D., Fischer, M.L., Kirchstetter, T.W., Brown, N.J., Hering, S., Stolzenburg, M. |
Type: Report |
| Report number: LBNL-46199 |
Year: 2001 |
| Title: Comparison of sampling methods for semi-volatile organic carbon (SVOC) |
Published in: Aerosol Science and Technology, Volume 34, Pages 9-22. |
| Authors: Lewtas, J., Booth, D., Pang, Y., Reimer, S., Eatough, D.J., Gundel, L A. |
Type: Journal Article |
| Report number: |
Year: 2000 |
| Title: A Concentration Rebound Method For Measuring Particle Penetration Into A Residence, Section 12A1 |
Published in: Proceedings of the 19th Annual American Association for Aerosol Research, St. Louis, MO. |
| Authors: Thatcher, T.L., Lunden, M.M., Fischer, M.L., Fine, J.D., Kirchstetter, T.W., Hering, S., Sextro, R.G., Brown, N.J. |
Type: Conference Proceedings |
| Report number: |
Year: 2000 |
| Title: Experimental Determination Of Size Resolved Particle Deposition Rates As A Function Of Room Furnishing And Room Air Velocity, Section 11PC |
Published in: Proceedings of the 19th Annual American Association of Aerosol Research, St. Louis, MO, Pages 332. |
| Authors: Thatcher, T.L., Lai, A.C.K., Moreno-Jackson, R., Sextro, R.G., Nazaroff, W.W. |
Type: Conference Proceedings |
| Report number: |
Year: 2000 |
| Title: A Predictive Model Of Indoor Concentrations Of Outdoor Pm-2.5 In Homes |
Published in: Proceedings of the 19th Annual American Association of Aerosol Research, St. Louis, MO, Volume Session 1A, Pages 5. |
| Authors: Lunden, M.M., Fischer, M.L., Fine, J.D., Thatcher, T.L., Kirchstetter, T.W., Hering, S., Sextro, R.G., Brown, N. J. |
Type: Conference Proceedings |
| Report number: LBNL-43711 |
Year: 1999 |
| Title: Determining transfer factors for outdoor aerosol plumes entering buildings |
Published in: Proceedings of the Indoor Air '99, Edinburgh, Scotland, Volume 5, Pages 331-334. |
| Authors: Thatcher, T.L., Nazaroff, W.W., Sextro, R.G. |
Type: Conference Proceedings |
| Report number: LBNL-42708 |
Year: 1999 |
| Title: Modeling aerosol behavior in multizone indoor environments |
Published in: Proceedings of the Indoor Air '99, Edinburgh, Scotland, Volume 4, Pages 785-790. |
| Authors: Sohn, M.D., A. Lai, B.V. Smith, R.G. Sextro, H.E. Feustel, W.W. Nazaroff |
Type: Conference Proceedings |
| Abstract: A publicly available aerosol dynamics model, MIAQ4, is coupled to a widely used multizone air flow and transport model, COMIS, to better understand and quantify the behavior of particles in indoor environments. MIAQ4 simulates the evolution of a size and chemically resolved particle distribution, including the effects of direct indoor emission, ventilation, filtration, deposition, and coagulation. COMIS predicts interzonal air-exchange rates based on pressure gradients (due to wind, buoyancy, and HVAC operation) and leaks between the zones and with the outside. The capabilities of the coupled system are demonstrated by predicting the transport of particles from two sources in a residence: environmental tobacco smoke (ETS) and particles generated from cooking. For ETS, MIAQ4 predicts particle size distributions that are similar to the emission source profile because ETS particles, concentrated in the size range 0.1 -- 1 ?m, are transformed by coagulation and deposition slowly compared with the rates of transport. For cooking, MIAQ4 predicts that the larger-sized particles will settle rapidly, causing a shift in size distribution as emissions are transported to other rooms. |
| Report number: LBNL-42710 |
Year: 1999 |
| Title: Particle deposition from turbulent duct flow |
Published in: Proceedings of the Indoor Air '99, Edinburgh, Scotland, Volume 2, Pages 24-29. |
| Authors: Sippola, M.R., Nazaroff, W.W., Thatcher, T.L. |
Type: Conference Proceedings |
| Report number: LBNL-43174 |
Year: 1999 |
| Title: Particle Concentrations in an Air-Conditioned Office Building with Normal and High Efficiency Filtration |
Published in: Proceedings of the Indoor Air '99, Edinburgh, Scotland, Volume 4, Pages 19-24. |
| Authors: Fisk, W.J., Sullivan, D., Mendell, M. |
Type: Conference Proceedings |
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