Fog Spraying Deposition of Wood Cellulose Nanofibers Containing Tert‐Butanol on Tissue Paper for Air Filtration

This study describes a significant upgrade to the particulate matter (PM) size disaggregation profile library used for preparing emissions files for the GEM-MACH (Global Environmental Multiscale-Modelling Air-quality and CHemistry) chemical transport model (CTM). This model uses a sectional (bin) approach to represent the PM size distribution, where one configuration employs 12 size bins to disaggregate PM2.5 and PM10 inventory emissions into the first 10 bins ranging from 0.01 to 10.24 μm in diameter. For the size disaggregation step, a small library of three generic PM size disaggregation profiles is currently applied for three broad source categories (area, mobile, and point). However, as might be expected, these generic profiles are not always representative: for example, emissions from two very different area sources ‒ paved road dust and residential wood combustion ‒ are disaggregated using the same generic size distribution profile. In order to improve the current small PM size disaggregation profile library, a comprehensive literature review was conducted: over 100 relevant publications were identified and PM size distribution profiles for 36 different emission source types were selected and compiled. These 36 source-type-specific PM size distribution profiles were then combined based on process type with corresponding PM speciation profiles to create a library of chemically speciated and size-resolved PM disaggregation profiles. This library can now be used by the SMOKE (Sparse Matrix Operator Kernel Emissions) emissions processing system for the 12-bin version of GEM-MACH to perform PM chemical speciation and size allocation in one step. The size-profile data collected and compiled in this study may also be used for emissions processing for other CTMs with a size-resolved representation of PM. Details of the compilation of the 36 PM size disaggregation profiles are discussed, and the differences in processed PM emissions based on the current and updated PM size disaggregation profile libraries are shown. Implications: A new and expanded particulate matter (PM) size disaggregation profile library covering 36 emission source types has been developed based on an extensive literature review. Its use can produce significant changes in the size allocation of bulk PM inventory emissions processed for input to size-resolved PM chemical transport models. Such models are used to predict atmospheric visibility and to simulate the interactions of aerosol particles with atmospheric radiation and with clouds. The use of more accurate, size-resolved primary PM emissions by these models should improve their predictive skill for atmospheric PM processes affecting air quality, meteorology, and climate.

Smoke emissions and particulate matter (PM) size distributions were investigated on a direct-injection single-cylinder diesel engine running on both gas-to-liquid (GTL) and diesel fuels utilizing a novel spiral-helical intake manifold design. Smoke opacity was measured at a wide range of engine loads and speeds with both fuels to examine the effect of using the new manifold on smoke emissions. In addition, total PM numbers of fine particles (PM diameter = 1.0 µm) and coarse particles (>1.0 µm) were quantified with both fuels. Moreover, high-resolution transmission electron microscopy (HRTEM) images were taken with different resolutions to observe the PM sizes produced from each fuel when using the new and normal manifolds. The results showed that using the novel manifold reduced smoke emissions for both GTL and diesel fuels with about 36% at low loads and 7% at high loads. However, using the new manifold with GTL fuel showed superior performance to reduce smoke with about 60% at low loads and 10% at high loads. For the PM size distribution, the new manifold reduced total PM emissions in general. However, significant reductions were obtained with fine PM sizes (0.3 – 1.0 µm) when GTL fuel was used with about 30% for constant load tests, and about 40% for constant speed tests. On the other hand, the new manifold tended to increase slightly the coarse PM sizes. The HRTEM images of the PM structure for both manifolds and fuels have confirmed the above results.

<div class="htmlview paragraph">An experimental study was performed to investigate diesel particulate filter (DPF) performance during filtration with the use of real-time measurement equipment. Three operating conditions of a single-cylinder 2.3-liter D.I. heavy-duty diesel engine were selected to generate distinct types of diesel particulate matter (PM) in terms of chemical composition, concentration, and size distribution. Four substrates, with a range of geometric and physical parameters, were studied to observe the effect on filtration characteristics. Real-time filtration performance indicators such as pressure drop and filtration efficiency were investigated using real-time PM size distribution and a mass analyzer. Types of filtration efficiency included: mass-based, number-based, and fractional (based on particle diameter). In addition, time integrated measurements were taken with a Rupprecht & Patashnick Tapered Element Oscillating Microbalance (TEOM), Teflon and quartz filters.</div> <div class="htmlview paragraph">Initial breakthrough phenomenon was observed for all clean DPFs. As the soot cake layer forms on top the substrate, the filtration efficiency is improved. In reality, the DPF substrate itself has poor filtration efficiency. It acts more as a facilitator to form a soot cake for the filtration of diesel particulates. A lower pressure drop filter (with approximately 70% larger filtration area than the others tested) showed considerably longer initial breakthrough. Results show different engine operating conditions resolve into distinct PM concentration, chemical composition, size distribution, and filtration velocity. Differences in the particulate composition and filtration characteristics appear to influence DPF pressure drop and filtration performance. Although the coating of the substrate contributes to higher pressure drop, it does not influence the onset of the different stages of filling. Comparing substrates with different geometrical and physical properties, a shift of the most penetrating particle range (Greenfield Gap) was observed.</div>

<div class="htmlview paragraph">The measuring method of vehicular particulate matter (PM) size distribution to simulate the atmospheric dilution process was studied. PM size distribution was measured with a scanning mobility particle sizer (SMPS). To simulate the atmospheric dilution process with a chassis dynamometer test, a chasing experiment was done in order to obtain reference data. A light duty diesel truck was selected as a basic test vehicle. Three sizes of prototype partial flow diluters (PPFD) were made to reproduce the PM size in the atmosphere. The PM sizes of the chasing experiment and the PPFD experiment was roughly agreed. Differences in the data obtained from a full flow dilution tunnel and the chasing experiments were investigated. The length of the transfer tube greatly affected the smaller side of the PM number concentration.</div>

Version 4.10s of the comprehensive air‐quality model with extensions (CAMx) photochemical grid model has been developed, which includes two options for representing particulate matter (PM) size distribution: (1) a two-section representation that consists of fine (PM2.5) and coarse (PM2.5–10) modes that has no interactions between the sections and assumes all of the secondary PM is fine; and (2) a multisectional representation that divides the PM size distribution into N sections (e.g., N = 10) and simulates the mass transfer between sections because of coagulation, accumulation, evaporation, and other processes. The model was applied to Southern California using the two‐section and multisection representation of PM size distribution, and we found that allowing secondary PM to grow into the coarse mode had a substantial effect on PM concentration estimates. CAMx was then applied to the Western United States for the 1996 annual period with a 36‐km grid resolution using both the two-section and multisection PM representation. The Community Multiscale Air Quality (CMAQ) and Regional Modeling for Aerosol and Deposition (REMSAD) models were also applied to the 1996 annual period. Similar model performance was exhibited by the four models across the Interagency Monitoring of Protected Visual Environments (IMPROVE) and Clean Air Status and Trends Network monitoring networks. All four of the models exhibited fairly low annual bias for secondary PM sulfate and nitrate but with a winter overestimation and summer underestimation bias. The CAMx multisectional model estimated that coarse mode secondary sulfate and nitrate typically contribute <10% of the total sulfate and nitrate when averaged across the more rural IMPROVE monitoring network.

BackgroundAmbient particulate matter (PM) exposure is associated with respiratory and cardiovascular morbidity and mortality. To what extent such effects are different for PM obtained from different sources or locations is still unclear. This study investigated the in vitro toxicity of ambient PM collected at different sites in the Netherlands in relation to PM composition and oxidative potential.MethodPM was sampled at eight sites: three traffic sites, an underground train station, as well as a harbor, farm, steelworks, and urban background location. Coarse (2.5-10 μm), fine (< 2.5 μm) and quasi ultrafine PM (qUF; < 0.18 μm) were sampled at each site. Murine macrophages (RAW 264.7 cells) were exposed to increasing concentrations of PM from these sites (6.25-12.5-25-50-100 μg/ml; corresponding to 3.68-58.8 μg/cm2). Following overnight incubation, MTT-reduction activity (a measure of metabolic activity) and the release of pro-inflammatory markers (Tumor Necrosis Factor-alpha, TNF-α; Interleukin-6, IL-6; Macrophage Inflammatory Protein-2, MIP-2) were measured. The oxidative potential and the endotoxin content of each PM sample were determined in a DTT- and LAL-assay respectively. Multiple linear regression was used to assess the relationship between the cellular responses and PM characteristics: concentration, site, size fraction, oxidative potential and endotoxin content.ResultsMost PM samples induced a concentration-dependent decrease in MTT-reduction activity and an increase in pro-inflammatory markers with the exception of the urban background and stop & go traffic samples. Fine and qUF samples of traffic locations, characterized by a high concentration of elemental and organic carbon, induced the highest pro-inflammatory activity. The pro-inflammatory response to coarse samples was associated with the endotoxin level, which was found to increase dramatically during a three-day sample concentration procedure in the laboratory. The underground samples, characterized by a high content of transition metals, showed the largest decrease in MTT-reduction activity. PM size fraction was not related to MTT-reduction activity, whereas there was a statistically significant difference in pro-inflammatory activity between Fine and qUF PM. Furthermore, there was a statistically significant negative association between PM oxidative potential and MTT-reduction activity.ConclusionThe response of RAW264.7 cells to ambient PM was markedly different using samples collected at various sites in the Netherlands that differed in their local PM emission sources. Our results are in support of other investigations showing that the chemical composition as well as oxidative potential are determinants of PM induced toxicity in vitro.

Following the examination and evaluation of 12 nucleation parameterizations presented in part 1, 11 of them representing binary, ternary, kinetic, and cluster‐activated nucleation theories are evaluated in the U.S. Environmental Protection Agency Community Multiscale Air Quality (CMAQ) modeling system version 4.4. The 12–28 June 1999 Southern Oxidants Study episode is selected as a testbed to evaluate simulated particulate matter (PM) number and size predictions of CMAQ with different nucleation parameterizations. The evaluation shows that simulated domain‐wide maximum PM2.5 number concentrations with different nucleation parameterizations can vary by 3 orders of magnitude. All parameterizations overpredict (by a factor of 1.4 to 1.7) the total number concentrations of accumulation‐mode PM and significantly underpredict (by factors of 1.3 to 65.7) those of Aitken‐mode PM, resulting in a net underprediction (by factors of 1.3 to 13.7) of the total number concentrations of PM2.5 under a polluted urban environment at a downtown station in Atlanta. The predicted number concentrations for Aitken‐mode PM at this site can vary by up to 3 orders of magnitude, and those for accumulation‐mode PM can vary by up to a factor of 3.2, with the best predictions by the power law of Sihto et al. (2006) (NMB of −31.7%) and the worst predictions by the ternary nucleation parameterization of Merikanto et al. (2007) (NMB of −93.1%). The ternary nucleation parameterization of Napari et al. (2002) gives relatively good agreement with observations but for a wrong reason. The power law of Kuang et al. (2008) and the binary nucleation parameterization of Harrington and Kreidenweis (1998) give better agreement than the remaining parameterizations. All the parameterizations fail to reproduce the observed temporal variations of PM number, volume, and surface area concentrations. The significant variation in the performance of these parameterizations is caused by their different theoretical bases, formulations, and dependence on temperature, relative humidity, and the ambient levels of H2SO4 and NH3. The controlling processes are different for PM number, mass, and surface areas. At urban/rural locations, some PM processes (e.g., homogeneous nucleation) and/or vertical transport may dominate the production of PM2.5 number, and emissions, or PM processes, or vertical transport or their combinations may dominate the production of PM2.5 mass and surface area. Dry deposition or some PM processes such as coagulation may dominate PM2.5 number loss, and horizontal and vertical transport, and cloud processes (e.g., cloud scavenging and wet deposition) may dominate the loss of PM2.5 mass and surface area concentrations. Sensitivity simulations show that the PM number and size distribution predictions are most sensitive to prescribed emission fractions of Aitken and accumulation‐mode PM and the assumed initial PM size distribution, in addition to different nucleation parameterizations.

Atmospheric particulate matter from an industrial area as a source of metal nanoparticle contamination in aquatic ecosystems

Context: Strong epidemiological evidence exists linking particulate matter (PM) exposures with hospital admissions of individuals for cardiopulmonary symptoms. The PM size is important in influencing the extent of infiltration into the respiratory tract and systemic circulation and directs the differential physiological impacts.Objective: To investigate the differential effects of the quasi-ultrafine (PM0.2), fine (PM0.15-2.5), and coarse PM (PM2.5-10) size fractions on pulmonary and cardiac function.Methods: Female BALB/c mice were exposed to HEPA-filtered laboratory air or concentrated coarse, fine, or quasi-ultrafine PM using Harvard Ambient Particle Concentrators in conjunction with our nose-only exposure system. These exposures were conducted as part of the “Health Effects of Aerosols in Toronto (HEAT)” campaign. Following a 4 h exposure, mice underwent assessment of respiratory function and recording of electrocardiograms using the flexiVent® system.Results: Exposure to coarse and fine PM resulted in a significant reduction in quasistatic compliance of the lung. Baseline total respiratory resistance and maximum responsiveness to methacholine were augmented after coarse PM exposures but were not affected by quasi-ultrafine PM exposures. In contrast, quasi-ultrafine PM alone had a significant effect on heart rate and in reducing heart rate variability.Conclusion: These findings indicate that coarse and fine PM influence lung function and airways responsiveness, while ultrafine PM can perturb cardiac function. This study supports the hypothesis that coarse and fine PM exerts its predominant physiologic effects at the site of deposition in the airways, whereas ultrafine PM likely crosses the alveolar epithelial barrier into the systemic circulation to affect cardiovascular function.

Rapid growth in industrialization and urbanization in Karachi draws attention toward increasing rate of air pollution and its health effects. So, the main objective of the present study was to determine the root cause of daily morbidity associated with airborne particulate matter (PM) exposure in Karachi. Other goal was to highlight those areas which are severely at the risk of particulate matter hazards. For this, high volume air sampler was used to collect PM from both indoor and outdoor air at commercial, residential and educational environments of Karachi. Effect of meteorological parameters on PM was also investigated. Heavy metals (Cd, Pb and Cu) concentrations in PM were determined by atomic absorption spectroscopy, while other elemental composition, morphology and size of PM were analyzed by scanning electron microscopy–energy-dispersive X-ray spectroscopy. The results revealed that PM particles consisted of O, Si, Ca, Cl, S, Na, C, Fe, Cd, Pb, Cu, Mg, Al, Zn, K and Ba. The morphologies of PM were spheroidal, irregular, fractal, narrow elongated, crystalline tabular and fiber like. The indoor and outdoor air at commercial sites (e.g., open markets) was not found suitable from health perspective. Especially, the area of Manghopir road has almost four times higher Pb concentration (1.879 µg/m3) than the WHO standard (0.5 µg/m3). The size range of particles in both outdoor (0.119–1.63 µm) and indoor (0.13–1.02 µm) settings existed in the category of PM2.5. Therefore, these fine particles with hazardous chemical composition and morphology are liable for daily morbidity of exposed population.

Measuring ambient particulate matter in three cities in Cameroon, Africa

Soil organic matter at a depth of 0–55 cm, collected from a Japanese larch forest area, was separated into particulate organic matter (size >53 μm), particulate organic matter (size <53 μm) and humic acid matter. Depth profiles of their Δ14C and δ13C values were determined. The Δ14C values of particulate matters decreased greatly from 128‰ to -278‰, indicating a relative increase of resistant organic components in particulate matters. That of humic acid matter decreased from 183‰ to -139‰. For these of organic matter fractions at the same depth, the Δ14C values of particulate matter (size > 53 μm) are smallest and those of humic acid matter are the largest. That indicates that a high contribution of young organic matter to the humic acid matter exists and transformation tendency of particulate matter may be from coarse to small in the particulate size. Positive Δ14C values appeared at a depth of 10 cm, 25 cm, and 35 cm for the particulate organic matter (size > 53 μm), particulate organic matter (size <53 μm) and humic acid matter, respectively. The transformation rate is suggested to be different in different organic matter. Positive Δ14C values of the humic acid matter also infects that the bomb carbon has reached the depth of 35 cm. Additionally, the Δ14C values of these three kinds of organic matters ranged from 50‰ to 183‰ at a depth of 0–7 cm, which were not smaller than that of litter in the forest area, indicating high proportion of modern, plants-derived soil organic matter in this depth ranges. The δ13C values increased from −28‰ to −23‰ with the increase depth of 0–55 cm. The δ13C values of humic acid matter are approximately less than that of particulate matters at the same depth, which may be explained as a high contribution of young organic matter to the humic acid matter.

The correlation of immunotoxicity with size and chemical properties of particulate matter within macrophages.

This study was carried out to provide preliminary information to grasp how many particulate matter (PM) which is a problem in urban area are absorbed and removed by street trees. The morphology, size and element composition of PM deposited on leaves of five street trees (Quercus glauca, Q. myrsinaefolia, Ginkgo biloba, Prunus serrulata var. spontanea, and Pinus densiflora) in Jinju city, South Korea were analyzed. The size of PM was classified into three as PM2.5 (0.2~2.5 μm), PM10 (2.5~10 μm), and PM100 (10~100 μm). The element composition of PM deposited on the leaves at the study sites mainly comprised of O, C, N, Si, and Al. The PM at industrial area and university campus was irregular and spherical shape, respectively. Total PM accumulated on the leaf surfaces of P. densiflora was 71.65 μg/cm2 at industrial area and 40.66 μg/cm2 at university campus, which was significantly higher than the other species. The ratio of PM2.5, PM10, and PM100 deposited on the leaves was 9.2%, 37.0%, 53.8% at industrial area and 15.8%, 27.1%, 57.1% at university campus, respectively. P. densiflora deposited the most PM2.5, PM10 and PM100 in leaf wax at the study sites, which was significantly higher than the other species. Key words: element composition, in-wax PM, leaf surface PM, urban environment, street trees

Background:Observed seasonal differences in particulate matter (PM) associations with human health may be due to their composition and to toxicity-related seasonal interactions.Objectives:We assessed seasonality in PM composition and in vitro PM pro-inflammatory potential using multiple PM samples.Methods:We collected 90 weekly PM10 and PM2.5 samples during the rainy-warm and dry-cold seasons in five urban areas with different pollution sources. The elements, polycyclic aromatic hydrocarbons (PAHs), and endotoxins identified in the samples were subjected to principal component analysis (PCA). We tested the potential of the PM to induce tumor necrosis factor alpha (TNFα) and interleukin 6 (IL-6) secretion in cultured human monocytes (THP-1), and we modeled pro-inflammatory responses using the component scores.Results:PM composition varied by size and by season. PCA identified two main components that varied by season. Combustion-related constituents (e.g., vanadium, benzo[a]pyrene, benzo[a]anthracene) mainly comprised component 1 (C1). Soil-related constituents (e.g., endotoxins, silicon, aluminum) mainly comprised component 2 (C2). PM from the rainy-warm season was high in C2. PM (particularly PM2.5) from the dry-cold season was rich in C1. Elevated levels of cytokine production were associated with PM10 and C2 (rainy-warm season), whereas reduced levels of cytokine production were associated with PM2.5 and C1 (dry-cold season). TNFα secretion was increased following exposure to PM with high (vs. low) C2 content, but TNFα secretion in response to PM was decreased following exposure to samples containing ≥ 0.1% of C1-related PAHs, regardless of C2 content. The results of the IL-6 assays suggested more complex interactions between PM components and particle size.Conclusions:Variations in PM soil and PAH content underlie seasonal and PM size–related patterns in TNFα secretion. These results suggest that the mixture of components in PM explains some seasonal differences in associations between health outcomes and PM in epidemiologic studies.Citation:Manzano-León N, Serrano-Lomelin J, Sánchez BN, Quintana-Belmares R, Vega E, Vázquez-López I, Rojas-Bracho L, López-Villegas MT, Vadillo-Ortega F, De Vizcaya-Ruiz A, Rosas Perez I, O’Neill MS, Osornio-Vargas AR. 2016. TNFα and IL-6 responses to particulate matter in vitro: variation according to PM size, season, and polycyclic aromatic hydrocarbon and soil content. Environ Health Perspect 124:406–412; http://dx.doi.org/10.1289/ehp.1409287