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Air Pollutants (air + pollutant)
Kinds of Air Pollutants Selected AbstractsUNSTEADY STATE DISPERSION OF AIR POLLUTANTS UNDER THE EFFECTS OF DELAYED AND NONDELAYED REMOVAL MECHANISMSNATURAL RESOURCE MODELING, Issue 4 2009MANJU AGARWAL Abstract In this paper, we present a two-dimensional time-dependent mathematical model for studying the unsteady state dispersion of air pollutants emitted from an elevated line source in the atmosphere under the simultaneous effects of delayed (slow) and nondelayed (instantaneous) removal mechanisms. The wind speed and coefficient of diffusion are taken as functions of the vertical height above the ground. The deposition of pollutants on the absorptive ground and leakage into the atmosphere at the inversion layer are also included in the model by applying appropriate boundary conditions. The model is solved numerically by the fractional step method. The Lagrangian approach is used to solve the advection part, whereas the Eulerian finite difference scheme is applied to solve the part with the diffusion and removal processes. The solutions are analyzed to observe the effects of coexisting delayed and nondelayed removal mechanisms on overall dispersion. Comparison of delayed and nondelayed removal processes of equal capacity shows that the latter (nondelayed) process is more effective than the former (delayed removal) in the removal of pollutants from the atmosphere. [source] Exposure to cadmium-contaminated soils increases allergenicity of Poa annua L. pollenALLERGY, Issue 10 2010R. Aina To cite this article: Aina R, Asero R, Ghiani A, Marconi G, Albertini E, Citterio S. Exposure to cadmium-contaminated soils increases allergenicity of Poa annua L. pollen. Allergy 2010; 65: 1313,1321. Abstract Background:, Pollution is considered as one main cause for the increase of allergic diseases. Air pollutants may cause and worsen airway diseases and are probably able to make pollen allergens more aggressive. Previous studies looked at traffic-related air pollution, but no data about the effects of polluted soils on pollen allergens are available. We aimed to assess the effects of plant exposure to cadmium-contaminated soil on allergenicity of the annual blue grass, Poa annua L, pollen. Methods:,Poa plants were grown in soil contaminated or not contaminated (control) with cadmium. At flowering, mature pollen was analyzed by microscopy, to calculate the percentage of pollen grains releasing cytoplasmic granules, and by proteomic techniques to analyze allergen proteins. Allergens were identified by sera from grass pollen,allergic patients and by mass spectrometry. Results:, Pollen from Cd-exposed plants released a higher amount of allergenic proteins than control plants. Moreover, Cd-exposed pollen released allergens-containing cytoplasmic grains much more promptly than control pollen. Group 1 and 5 allergens, the major grass pollen allergens, were detected both in control and Cd-exposed extracts. These were the only allergens reacting with patient's sera in control pollen, whereas additional proteins strengthening the signal in the gel region reacting with patient's sera were present in Cd-exposed pollen. These included a pectinesterase, a lipase, a nuclease, and a secretory peroxydase. Moreover, a PR3 class I chitinase-like protein was also immunodetected in exposed plants. Conclusion:, Pollen content of plants grown in Cd-contaminated soils is more easily released in the environment and also shows an increased propensity to bind specific IgE. [source] The short-term effects of air pollution on daily mortality in four Australian citiesAUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH, Issue 3 2005Rod Simpson Objective: To examine the short-term health effects of air pollution on daily mortality in four Australian cities (Brisbane, Melbourne, Perth and Sydney), where more than 50% of Australians reside. Methods: The study used a similar protocol to APHEA2 (Air Pollution and Health: A European Approach) study and derived single-city and pooled estimates. Results: The results derived from the different approaches for the 1996-99 period showed consistent results for different statistical models used. There were significant effects on total mortality, (RR=1.0284 per 1 unit increase in nephelometry [10 -4. m -1], RR=1.0011 per 1ppb increase in NO2), and on respiratory mortality (RR=1.0022 per 1ppb increase in O3). No significant differences between cities were found, but the NO2 and particle effects may refer to the same impacts. Meta-analyses carried out for three cities yielded estimates for the increase in the daily total number of deaths of 0.2% (-0.8% to 1.2%) for a 10 ,g/m3 increase in PM10 concentration, and 0.9% (-0.7% to 2.5%) for a 10 ,g/m3 increase in PM2.5 concentration. Conclusions: Air pollutants in Australian cities have significant effects on mortality. [source] Air pollution impedes plant-to-plant communication by volatilesECOLOGY LETTERS, Issue 9 2010James D. Blande Ecology Letters (2010) 13: 1172,1181 Abstract Volatile organic compounds (VOCs) emitted by damaged plants convey information to undamaged neighbouring plants, and previous research has shown that these signals are effective over short distances in nature. Many herbivore-induced VOCs react with ozone, which is the most important tropospheric air pollutant in rural areas. We used extrafloral nectar (EFN) secretion as a phenotypic indicator of between-plant communication in Phaseolus lunatus L. (Lima bean) and show that an ozone-rich (80 ppb) atmosphere reduces the distance over which signalling occurs. We found that ozone degrades several herbivore-induced VOCs, a likely mechanism reducing communication distances. Direct exposure to 80-ppb ozone did not affect the VOC emissions from P. lunatus. In addition, we demonstrated that high ozone concentrations, 120 and 160 ppb, induced EFN secretion in exposed plants, whereas more moderate concentrations, 80 and 100 ppb, did not. This suggests that ozone can play a complex role in the indirect defence of P. lunatus. [source] Expression of caspase and apoptotic signal pathway induced by sulfur dioxideENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2 2010Juli Bai Abstract Sulfur dioxide (SO2) is a common air pollutant that is released in low concentrations into the atmosphere and in higher concentrations in some work places. In the present study, male Wistar rats were housed in exposure chambers and treated with 14.00 ± 1.01, 28.00 ± 1.77, and 56.00 ± 3.44 mg/m3 SO2 for 7 days (6 hr/day), while control rats were exposed to filtered air under the same conditions. The mRNA and protein levels of caspase-3, caspase-8, and caspase-9 were analyzed using a real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) assay and an immunohistochemistry method. Activities of caspases were detected using colorimetric and fluorescent assays. Chromatin degradation and cell morphological changes were investigated by TUNEL assay and H&E staining in livers and lungs, respectively. The results showed that mRNA levels, protein levels and activities of caspase-3, caspase-8, and caspase-9 were increased in a dose-dependent manner in livers and lungs of rats after SO2 inhalation. In addition, livers were infiltrated with lymphocytes, congestion and inflammation occurred in lungs, and eosinophil cells and apoptotic cells increased in both livers and lungs after SO2 inhalation. These results suggest that SO2 exposure increases the expression and activity of both initiator and and effector caspases, and may induce apoptosis in liver and lung of rats through both death receptor and mitochondrial pathways. Environ. Mol. Mutagen. 2010. © 2009 Wiley-Liss, Inc. [source] DNA damage in mice treated with sulfur dioxide by inhalationENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 3 2005Ziqiang Meng Abstract Sulfur dioxide (SO2) is a ubiquitous air pollutant produced by the burning of fossil fuels. In this study, single-cell gel electrophoresis (the Comet assay) was used to evaluate the DNA damage produced by inhalation exposure of mice to SO2. Male and female mice were housed in exposure chambers and treated with 14.00 ± 1.25, 28.00 ± 1.98, 56.00 ± 3.11, and 112.00 ± 3.69 mg/m3 SO2 for 6 hr/day for 7 days, while control groups were exposed to filtered air. Comet assays were performed on blood lymphocytes and cells from the brain, lung, liver, spleen, kidney, intestine, and testicles of the animals. SO2 caused significant, dose-dependent increases in DNA damage, as measured by Olive tail moment, in all the cell types analyzed from both sexes of mice. The results indicate that inhalation exposure to SO2 damages the DNA of multiple organs in addition to the lung, and suggests that this damage could result in mutation, cancer, and other diseases related to DNA damage. Further work will be required to understand the ultimate toxicological significance of this damage. These data also suggest that detecting DNA damage in blood lymphocytes, using the Comet assay, may serve as a useful tool for evaluating the impact of pulmonary SO2 exposure in human biomonitoring studies. Environ. Mol. Mutagen., 2005. © 2005 Wiley-Liss, Inc. [source] Nutrient limitations during the biofiltration of methyl isoamyl ketoneENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2005Hyun-Keun Son With biofiltration, both organic and inorganic compounds that are toxic to humans and volatile organic compounds from a variety of industrial and public sector sources have been effectively removed. During the initial stage of the acclimation period, the removal capacity of the biofilter is primarily attributed to the adsorption capacity of the media. The adsorption capacity of different types of biofilter media was studied. MIAK (methyl isoamyl ketone), which is one of the major air pollutants in painting operations, was used as the target air pollutant for the biofiltration experiments. All the materials tested exhibited very poor adsorption capacity for MIAK. The effect of nutrient limitation was also evaluated. A gradual decrease of removal capacity was observed under the nutrient-limited environment. When nutrient was provided to the biofilter, the removal capacity increased from 55 to 93% in 3 days. A nutrient ratio of chemical oxygen demand (COD):N:P = 200:4:1 was sufficient for the removal of volatile organic compounds from the polluted air stream. © 2004 American Institute of Chemical Engineers Environ Prog, 2004 [source] An evaluation of European air pollution regulations for particulate matter monitored from a heterogeneous networkENVIRONMETRICS, Issue 8 2009Sujit K. Sahu Abstract Statistical methods are needed for evaluating many aspects of air pollution regulations increasingly adopted by many different governments in the European Union. The atmospheric particulate matter (PM) is an important air pollutant for which regulations have been issued recently. A challenging task here is to evaluate the regulations based on data monitored on a heterogeneous network where PM has been observed at a number of sites and a surrogate has been observed at some other sites. This paper develops a hierarchical Bayesian joint space,time model for the PM measurements and its surrogate between which the exact relationship is unknown, and applies the methods to analyse spatio -temporal data obtained from a number of sites in Northern Italy. The model is implemented using MCMC techniques and methods are developed to meet the regulatory demands. These enablefull inference with regard to process unknowns, calibration, validation, predictions in time and space and evaluation of regulatory standards. Copyright © 2008 John Wiley & Sons, Ltd. [source] Bayesian analysis of dynamic factor models: an application to air pollution and mortality in São Paulo, BrazilENVIRONMETRICS, Issue 6 2008T. Sáfadi Abstract The Bayesian estimation of a dynamic factor model where the factors follow a multivariate autoregressive model is presented. We derive the posterior distributions for the parameters and the factors and use Monte Carlo methods to compute them. The model is applied to study the association between air pollution and mortality in the city of São Paulo, Brazil. Statistical analysis was performed through a Bayesian analysis of a dynamic factor model. The series considered were minimal temperature, relative humidity, air pollutant of PM10 and CO, mortality circulatory disease and mortality respiratory disease. We found a strong association between air pollutant (PM10), Humidity and mortality respiratory disease for the city of São Paulo. Copyright © 2007 John Wiley & Sons, Ltd. [source] The meta-analysis of the Italian studies on short-term effects of air pollution (MISA): old and new issues on the interpretation of the statistical evidencesENVIRONMETRICS, Issue 3 2007Pierantonio Bellini Abstract The second meta-analysis of the Italian studies on short-term health effects of air pollution, known as MISA-2, was based on daily time series of indicators of both pollution and of health outcomes. It covered 15 cities during 1996,2002 for a total population of approximately nine millions. Health outcomes included mortality for natural causes, for respiratory diseases and for cardiovascular conditions, as well as hospital admissions for respiratory, cardiac and cerebrovascular diseases. Pollutants considered in univariate analyses were sulphur dioxide (SO2), nitrogen oxide (NO2), carbon monoxide (CO), suspended particulate matter (SPM) measuring less than 10,µm diameter (PM10) and ozone (O3, limited to the summer period). Results, including risk estimates, have been largely confirmatory of findings obtained in previous large meta-analytic studies carried out in North America and in Europe. A full report in Italian is available. The present contribution summarises the results of MISA-2 and addresses three major issues regarding their interpretation: robustness of the causal inferential process, the role of specific air pollutants and the reliability of risk estimates. The former issue is stressed according to Bradford Hill's criteria and the conclusion is reached that at least for the association of air pollution with an increase in mortality the evidence for causality is strong. Assessing the role of each air pollutant is problematic: there is some evidence that the effects of PM10 are partly confounded by other pollutants, but PM10 may not be the best indicator of the role of air SPM (routine measures of PM2.5 have not been introduced in Italy). As for risk estimates, the per cent increase in risk of mortality for unit increase in PM10 concentration, measured in MISA-2, is remarkably similar to estimates in other studies and there is indication for linearity of the dose,response relationship. Copyright © 2007 John Wiley & Sons, Ltd. [source] Blur-generated non-separable space,time modelsJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES B (STATISTICAL METHODOLOGY), Issue 4 2000Patrick E. Brown Statistical space,time modelling has traditionally been concerned with separable covariance functions, meaning that the covariance function is a product of a purely temporal function and a purely spatial function. We draw attention to a physical dispersion model which could model phenomena such as the spread of an air pollutant. We show that this model has a non-separable covariance function. The model is well suited to a wide range of realistic problems which will be poorly fitted by separable models. The model operates successively in time: the spatial field at time t +1 is obtained by ,blurring' the field at time t and adding a spatial random field. The model is first introduced at discrete time steps, and the limit is taken as the length of the time steps goes to 0. This gives a consistent continuous model with parameters that are interpretable in continuous space and independent of sampling intervals. Under certain conditions the blurring must be a Gaussian smoothing kernel. We also show that the model is generated by a stochastic differential equation which has been studied by several researchers previously. [source] Association between atmospheric ozone levels and damage to human nasal mucosa in Florence, ItalyENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 3 2003Stefania Pacini Abstract We evaluated the effects of urban air pollutants on human nasal mucosa over an 8-month period on 102 subjects living in Florence, Tuscany, Italy. A group of subjects living in a city with a lower level of pollution (Sassari, Sardinia, Italy) was also analyzed. Nasal mucosa cells were harvested by brushing, a noninvasive procedure. Half of the cells were used for genotoxicity studies using the alkaline comet assay, and half for morphological studies. The levels of DNA damage in the nasal mucosa were considerably higher (+73%) in the subjects living in Florence than in Sassari. High levels of atmospheric ozone in Florence air correlated with DNA damage, and to the prevalence of inflammatory pathologies of the upper respiratory tract, although the ozone concentrations were below the Italian recommended attention level. Furthermore, higher levels of DNA damage were correlated with a dysfunction in the ability to maintain a normal epithelial cell structure. These data suggest an association between ozone air levels and damage in the upper respiratory tract. It remains unclear whether ozone itself or other associated pollutants are responsible for the observed alterations. Environ. Mol. Mutagen. 42:127,135, 2003. © 2003 Wiley-Liss, Inc. [source] Comparison of air quality management strategies of PM10, SO2, and NOx by an industrial source complex model in BeijingENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2007Gaoxiang Ying Abstract The primary air pollutants in the Beijing urban area are fine particulate matter (PM10), sulfur dioxide (SO2), and nitrogen oxides (NOx). Using suitable emission factors for point, area, and line sources from 20 categories of industrial, commercial, domestic and traffic, total yearly mean emissions were estimated at 103.3 kton of PM10, 209.9 kton of SO2, and 225.4 kton of NOx in 1999. To abate this elevated air pollution, three air quality management schemes are adopted. After the implementation, the annual mean ground-level concentrations of air pollutants are predicted by an industrial source complex short term (ISCST3) dispersion model and compared by the geographic information system (GIS). The ISCST3 dispersion model is used by inputting emission inventory and meteorological data with 1 h temporal and 1 km × 1 km spatial resolution. The model validity is verified by its agreement with monitoring data from Beijing's Environmental Protection Bureau. Results indicate that the levels of PM10, SO2, and NOx in Beijing are improved gradually because of the adoption of these three control schemes. The predicted annual mean concentrations decreased from 90.63 to 67.28 ,g/m3 for PM10, 57.94 to 31.77 ,g/m3 for SO2, and 119.97 to 73.83 ,g/m3 for NOx, respectively. © 2007 American Institute of Chemical Engineers Environ Prog 26:33,42, 2007. [source] Photocatalytic oxidation of methanol using silica-titania composites in a packed-bed reactorENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 4 2006Jennifer M. Stokke Abstract The processing of forest products into pulp, paper, paperboard, and other wood products results in the generation of volatile organic compounds (VOCs) and hazardous air pollutants (HAPs). This work focused on the development of a photocatalytic packed-bed reactor for the oxidation of methanol, which is the primary constituent in high volume low concentration gases emitted from pulp and paper mills. Bench-scale studies using an annular reactor packed with silica-titania composite (STC) pellets were conducted to maximize methanol removal and minimize the formation of byproducts, such as formaldehyde. Parameters such as STC pore size (ca. 40, 120, and 260 Å) and UV wavelength (UVA and UVC) were varied. In the dark, the STC pellets removed methanol via adsorption and had a finite adsorption capacity dependent on the surface area of the composite. When irradiated with UV light, the STC pellets adsorbed and oxidized methanol simultaneously. At the bench-scale, 40 Å STC pellets irradiated with UVC light achieved the greatest methanol removal (ca. 90%) with minimal byproduct formation (i.e., effluent formaldehyde concentration was <1 ppmv). Based on these results, a 40 acfm pilot reactor was fabricated and achieved methanol removal rates up to 66% ± 7% with <1 ppmv formaldehyde production at steady state. © 2006 American Institute of Chemical Engineers Environ Prog, 2006 [source] Nutrient limitations during the biofiltration of methyl isoamyl ketoneENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2005Hyun-Keun Son With biofiltration, both organic and inorganic compounds that are toxic to humans and volatile organic compounds from a variety of industrial and public sector sources have been effectively removed. During the initial stage of the acclimation period, the removal capacity of the biofilter is primarily attributed to the adsorption capacity of the media. The adsorption capacity of different types of biofilter media was studied. MIAK (methyl isoamyl ketone), which is one of the major air pollutants in painting operations, was used as the target air pollutant for the biofiltration experiments. All the materials tested exhibited very poor adsorption capacity for MIAK. The effect of nutrient limitation was also evaluated. A gradual decrease of removal capacity was observed under the nutrient-limited environment. When nutrient was provided to the biofilter, the removal capacity increased from 55 to 93% in 3 days. A nutrient ratio of chemical oxygen demand (COD):N:P = 200:4:1 was sufficient for the removal of volatile organic compounds from the polluted air stream. © 2004 American Institute of Chemical Engineers Environ Prog, 2004 [source] Air Pollution from Secondary Aluminum Production: Determining the Applicability of MACT RequirementsENVIRONMENTAL QUALITY MANAGEMENT, Issue 4 2001Mario G. Cora EPA's Maximum Achievable Control Technology rule for secondary aluminum production is intended to substantially reduce emissions of hazardous air pollutants. It may also impose significant costs on affected facilities. © 2001 John Wiley & Sons, Inc. [source] The meta-analysis of the Italian studies on short-term effects of air pollution (MISA): old and new issues on the interpretation of the statistical evidencesENVIRONMETRICS, Issue 3 2007Pierantonio Bellini Abstract The second meta-analysis of the Italian studies on short-term health effects of air pollution, known as MISA-2, was based on daily time series of indicators of both pollution and of health outcomes. It covered 15 cities during 1996,2002 for a total population of approximately nine millions. Health outcomes included mortality for natural causes, for respiratory diseases and for cardiovascular conditions, as well as hospital admissions for respiratory, cardiac and cerebrovascular diseases. Pollutants considered in univariate analyses were sulphur dioxide (SO2), nitrogen oxide (NO2), carbon monoxide (CO), suspended particulate matter (SPM) measuring less than 10,µm diameter (PM10) and ozone (O3, limited to the summer period). Results, including risk estimates, have been largely confirmatory of findings obtained in previous large meta-analytic studies carried out in North America and in Europe. A full report in Italian is available. The present contribution summarises the results of MISA-2 and addresses three major issues regarding their interpretation: robustness of the causal inferential process, the role of specific air pollutants and the reliability of risk estimates. The former issue is stressed according to Bradford Hill's criteria and the conclusion is reached that at least for the association of air pollution with an increase in mortality the evidence for causality is strong. Assessing the role of each air pollutant is problematic: there is some evidence that the effects of PM10 are partly confounded by other pollutants, but PM10 may not be the best indicator of the role of air SPM (routine measures of PM2.5 have not been introduced in Italy). As for risk estimates, the per cent increase in risk of mortality for unit increase in PM10 concentration, measured in MISA-2, is remarkably similar to estimates in other studies and there is indication for linearity of the dose,response relationship. Copyright © 2007 John Wiley & Sons, Ltd. [source] Spatial-temporal model for ambient air pollutants in the state of KuwaitENVIRONMETRICS, Issue 7 2006Fahimah A. Al-Awadhi Abstract In this paper we consider dynamic Bayesian models for four different pollutants: nitric oxide(NO), carbon monoxide(CO), sulphur dioxide(SO2) and non-methane hydrocarbon (NCH4) recorded daily in six different stations in Kuwait from 1999 to 2002. The structure of the models depends on time, space and pollutants dependencies. The approach strives to incorporate the uncertainty of the covariance structure into simulated models and final inference; therefore, hierarchical Bayesian model is applied. Association between level of pollutants and different meteorological variables, such as wind speed, wind directions, temperature and humidity are considered. The models will decompose into two main components: a deterministic part to represent the observed components term and a stochastic term to represent the unobservable components. Our analysis will start with basic model and gradually increase its complexity. At each stage the efficiency of the model will be measured. The resulting models subsequently are tested by comparing the output terms and by comparing and the predictions with the real observations. Copyright © 2006 John Wiley & Sons, Ltd. [source] Analyzing weather effects on airborne particulate matter with HGLMENVIRONMETRICS, Issue 7 2003Yoon Dong Lee Abstract Particulate matter is one of the six constituent air pollutants regulated by the United States Environmental Protection Agency. In analyzing such data, Bayesian hierarchical models have often been used. In this article we propose the use of hierarchical generalized linear models, which use likelihood inference and have well developed model-checking procedures. Comparisons are made between analyses from hierarchical generalized linear models and Daniels et al.'s (2001) Bayesian models. Model-checking procedure indicates that Daniels et al.'s model can be improved by use of the log-transformation of wind speed and precipitation covariates. Copyright © 2003 John Wiley & Sons, Ltd. [source] Assessment of short-term association between health outcomes and ozone concentrations using a Markov regression modelENVIRONMETRICS, Issue 3 2003Abdelkrim Zeghnoun Abstract Longitudinal binary data are often used in panel studies where short-term associations between air pollutants and respiratory health outcomes are investigated. A Markov regression model in which the transition probabilities depend on the covariates, as well as the past responses, was used to study the short-term association between daily ozone (O3) concentrations and respiratory health outcomes in a panel of schoolchildren in Armentières, Northern France. The results suggest that there was a small but statistically significant association between O3 and children's cough episodes. A 10,,g/m3 increase in O3 concentrations was associated with a 13.9,% increase in cough symptoms (CI,95%,=,1.2,28.1%). The use of a Markov regression model can be useful as it permits one to address easily both the regression objective and the stochastic dependence between successive observations. However, it is important to verify the sensitivity of the Markov regression parameters to the time-dependence structure. In this study, it was found that, although what happened on the previous day was a strong predictor of what happened on the current day, this did not contradict the O3 -respiratory symptom associations. Compared to the Markov regression model, the signs of the parameter estimates of marginal and random-intercept models remain the same. The magnitudes of the O3 effects were also essentially the same in the three models, whose confidence intervals overlapped. Copyright © 2003 John Wiley & Sons, Ltd. [source] Analysis of particulate matter air pollution using Markov random field models of spatial dependenceENVIRONMETRICS, Issue 5-6 2002Mark S. Kaiser Abstract Researchers are beginning to realize the need to take spatial structure into account when modeling data on air pollutants. We develop several models for particulate matter in an urban region that allow spatial dependence to be represented in different manners over a time period of one year. The models are based on a Markov random field approach, and a conceptualization of observed data as arising from two random processes, a conditionally independent observation process and a spatially dependent latent pollution process. Optimal predictors are developed for both of these processes, and predictions of the observation process are used for model assessment. Copyright © 2002 John Wiley & Sons, Ltd. [source] Diffusion Characteristics of VOCs IndoorsIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 3 2010Shin-ichi Shibata Student Member Abstract Diffusion characteristics of volatile organic compounds (VOCs) were investigated indoors using tin oxide gas sensors. The chemicals cause various kinds of symptoms in humans, for example, the sick house syndrome. In this study, eight sensors were installed in a vertical direction and on a plane surface. These sensors were of the same type. The VOC is placed in a generation source, and the sensor output increases as the chemical diffuses. The sensor output becomes higher as the concentration increases. The following chemicals were tried as air pollutants: formaldehyde, toluene, and xylene. The sensor output changes in short, quick steps by slight fluctuations of the wind velocity. Therefore, the differential characteristic of the sensor output was adopted and the noise component was removed as far as possible. A threshold time tth to the characteristic was set up. It is assumed that the examining chemical reaches the installed sensor point in a time greater than this time. The new speed of arrival is proposed using the threshold time. The speed s [cm/min] is indicated using the distance d and the reaching time tth, namely, s = d/tth. Here, d means the distance between the sensor position and the polluting source. As a result, the speed for the sensor that is installed near the ceiling (at a height of 260 cm from the floor) is the highest. And, it became obvious that s was larger for the chemical with a smaller molecule. The speed of formaldehyde for the sensor installed near the ceiling was 700 cm/min and that for the sensor installed at the height of 100 cm from the floor was 370 cm/min. There is almost a two times difference in the speed. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Organic compounds as indicators of air pollutionINDOOR AIR, Issue 2003L. Mølhave Abstract The most important indoor air pollutants have already been addressed with individual national guidelines or recommendations. However, an international set of guidelines or recommendations for indoor air quality (IAQ) is needed for these pollutants based on general and uniform rules for setting such standards. A major research need exist on the less adverse pollutants before recommendations or guidelines can be established. In the interim period a precaution principle should lead to an ALARA principle for these secondary causalities. It should be noted that volatile organic compound (VOC) as an IAQ problem still is in the end of a phase of ad hoc solutions, in the middle of a research phase and only in the beginning of a regulatory phase. Any final official regulation in this area will have to be tentative and the final regulation must await further research. Total volatile organic compound (TVOC) is an indicator for the presence of VOC indoors. The TVOC indicator can be used in relation to exposure characterization and source identification but for VOCs only, not as an indictor of other pollutants and their health effects. In risk assessment the TVOC indicator can only be used as a screening tool and only for sensory irritation. [source] Statistical Assessment of Numerical Models,INTERNATIONAL STATISTICAL REVIEW, Issue 2 2003Montserrat Fuentes Summary Evaluation of physically based computer models for air quality applications is crucial to assist in control strategy selection. The high risk of getting the wrong control strategy has costly economic and social consequences. The objective comparison of modeled concentrations with observed field data is one approach to assessment of model performance. For dry deposition fluxes and concentrations of air pollutants there is a very limited supply of evaluation data sets. We develop a formal method for evaluation of the performance of numerical models, which can be implemented even when the field measurements are very sparse. This approach is applied to a current U.S. Environmental Protection Agency air quality model. In other cases, exemplified by an ozone study from the California Central Valley, the observed field is relatively data rich, and more or less standard geostatistical tools can be used to compare model to data. Yet another situation is when the cost of model runs is prohibitive, and a statistical approach to approximating the model output is needed. We describe two ways of obtaining such approximations. A common technical issue in the assessment of environmental numerical models is the need for tools to estimate nonstationary spatial covariance structures. We describe in detail two such approaches. Résumé L'évaluation de modèles informatiques à bases physiques pour des applications à la qualité de l'air est cruciale pour aider à la sélection d'une stratégie de contrôle. Le choix d'une mauvaise stratégie de contrôle peut avoir des conséquences economiques et sociales coúteuses. Une approche pour évaluer la performance du modèle est la comparaison objective de concentrations modélisées avec des données de terrain observées. Pour les flux de dépôts secs et les concentrations de polluants de l'air, l'offre de données d'évaluation est très limitée. Nous développons une méthode formelle pour évaluer la performance de modèles numériques, qui peut être mise en oeuvre même lorsque les mesures de terrain sont trés clairsemées. Cette approche est appliquée à un modèle de qualité de l'air de l'Agence de la Protection de l'Environnement Américaine. Dans d'autres cas, comme une étude de l'ozone de la vallée Californienne centrale, le champ observé est relativement riche en données, et l'on peut utiliser peu ou prou des outils géostatistiques standards pour comparer le modèle aux données. Une autre situation se présente quand le coút du modèle est prohibitif et qu'une approche statistique pour effectuer des approximations des sorties du modèle est nécessaire. Nous décrivons deux manières d'obtenir de telles approximations. Un problème technique commun à l'évaluation des modèles environnementaux numériques est le besoin d'outils pour estimer les structures de la covariance spatiale non stationnaire. Nous decrivons en detail deux de ces approches. [source] Bioprocesses for the removal of nitrogen oxides from polluted airJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2005Yaomin Jin Abstract Nitrogen oxides (NOx) of environmental concern are nitrogen monoxide (NO) and nitrogen dioxide (NO2). They are hazardous air pollutants that lead to the formation of acid rain and tropospheric ozone. Both pollutants are usually present simultaneously and are, therefore, called NOx. Another compound is N2O which is found in the stratosphere where it plays a role in the greenhouse effect. Concern for environmental and health issues coupled with stringent NOx emission standards generates a need for the development of efficient low-cost NOx abatement technologies. Under such circumstances, it becomes mandatory for each NOx-emitting industry or facility to opt for proper NOx control measures. Several techniques are available to control NOx emissions: selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR), adsorption, scrubbing, and biological methods. Each process offers specific advantages and limitations. Since bioprocesses present many advantages over conventional technologies for flue gas cleaning, a lot of interest has recently been shown for these processes. This article reviews the major characteristics of conventional non-biological technologies and recent advances in the biological removal of NOx from flue gases based on the catalytic activity of either eucaryotes or procaryotes, ie nitrification, denitrification, the use of microalgae, and a combined physicochemical and biological process (BioDeNOx). Relatively uncomplicated design and simple operation and maintenance requirements make biological removal a good option for the control of NOx emissions in stationary sources. Copyright © 2005 Society of Chemical Industry [source] A simple spatio-temporal procedure for the prediction of air pollution levelsJOURNAL OF CHEMOMETRICS, Issue 12 2002Jorge M. Mendes Abstract In this paper we study the spatio-temporal behaviour of air pollutants measured daily over the city of Lisbon, Portugal. Our specific aim is to predict air pollutant levels in time and space over a fine grid of locations based on observations from a small number of monitoring sites. Our suggested prediction procedure is based on the simple and intuitive idea of first making predictions in time at the monitoring sites and then extending these predictions in space to locations other than the monitoring sites using kriging methods. Copyright © 2002 John Wiley & Sons, Ltd. [source] The Watershed Deposition Tool: A Tool for Incorporating Atmospheric Deposition in Water-Quality Analyses,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 4 2009Donna B. Schwede Abstract:, A tool for providing the linkage between air and water-quality modeling needed for determining the Total Maximum Daily Load (TMDL) and for analyzing related nonpoint-source impacts on watersheds has been developed. Using gridded output of atmospheric deposition from the Community Multiscale Air Quality (CMAQ) model, the Watershed Deposition Tool (WDT) calculates average per unit area and total deposition to selected watersheds and subwatersheds. CMAQ estimates the wet and dry deposition for all of its gaseous and particulate chemical species, including ozone, sulfur species, nitrogen species, secondary organic aerosols, and hazardous air pollutants at grid scale sizes ranging from 4 to 36 km. An overview of the CMAQ model is provided. The somewhat specialized format of the CMAQ files is not easily imported into standard spatial analysis tools. The WDT provides a graphical user interface that allows users to visualize CMAQ gridded data and perform further analyses on selected watersheds or simply convert CMAQ gridded data to a shapefile for use in other programs. Shapefiles for the 8-digit (cataloging unit) hydrologic unit code polygons for the United States are provided with the WDT; however, other user-supplied closed polygons may be used. An example application of the WDT for assessing the contributions of different source categories to deposition estimates, the contributions of wet and dry deposition to total deposition, and the potential reductions in total nitrogen deposition to the Albemarle-Pamlico basin stemming from future air emissions reductions is used to illustrate the WDT capabilities. [source] Short-term effects of air pollution on cardiovascular diseases: outcomes and mechanismsJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 11 2007M. FRANCHINI Summary. The effects of air pollution on health have been intensively studied in recent years. Acute exposure to environmental pollutants such as particulate and gaseous matters (carbon monoxide, nitrogen oxides, sulphur dioxide and ozone) was associated with an increased rate of events and mortality because of cardiovascular diseases. These effects were investigated in short-term studies, which related day-to-day variations in air pollution to disease, and in long-term studies, which have followed cohorts of exposed individuals over time. The evidence from the literature on the short-term cardiovascular effects of air pollutants is discussed from clinical and mechanistic points of view. [source] Structural Disparities of Urban Traffic in Southern California: Implications for Vehicle-Related Air Pollution Exposure in Minority and High-Poverty NeighborhoodsJOURNAL OF URBAN AFFAIRS, Issue 5 2004Douglas Houston Emerging atmospheric science and epidemiological research indicates hazardous vehicle-related pollutants (e.g., diesel exhaust) are highly concentrated near major roadways, and the prevalence of respiratory ailments and mortality are heightened in these high-traffic corridors. This article builds on recent findings that low-income and minority children in California disproportionately reside in high-traffic areas by demonstrating how the urban structure provides a critical framework for evaluating the causes, characteristics, and magnitude of traffic, particularly for disadvantaged neighborhoods. We find minority and high-poverty neighborhoods bear over two times the level of traffic density compared to the rest of the Southern California region, which may associate them with a higher risk of exposure to vehicle-related pollutants. Furthermore, these areas have older and more multifamily housing, which is associated with higher rates of indoor exposure to outdoor pollutants, including intrusion of motor vehicle exhaust. We discuss the implications of these patterns on future planning and policy strategies for mitigating the serious health consequences of exposure to vehicle-related air pollutants. [source] The effects of allergens in outdoor air on both atopic and nonatopic subjects with airway diseaseALLERGY, Issue 5 2008P. G. J. Burney Background:, Reports on air pollution and asthma exacerbations have been inconsistent, although effects of airborne allergen can be spectacular. With no generalized test for allergen in air, it is not known how far allergen is responsible for nonepidemic exacerbations of the disease. Methods:, Two hundred and ninety-seven patients using bronchodilators aged 18,64 years attending a London practice provided serum samples and were asked to report any acute respiratory events over the coming months. Small particles with a mean aerodynamic diameter <10 ,m (PM10) were collected using a high volume sampler on the roof of the practice. The ability of airborne particles to bind IgE from the patients was compared for particles sampled on the weekend before their reported exacerbation with particles sampled on the weekend 2 weeks before or after. Results:, Exacerbations were associated with a 25% increase in IgE binding to particles collected on the previous weekend compared with the control weekends (95% confidence interval: 10,43%; P = 0.00089). This increase was not higher in patients with positive skin tests or in those sensitized to grass or tree pollens. Conclusions:, Airborne allergen is an important cause of exacerbations even in those with ,intrinsic' asthma. It is important to identify the allergens responsible, as some of these may be controllable. Interpretation of associations of asthma exacerbations with other air pollutants is difficult in the light of these findings. [source] | |||||||||||||||||||||||||