Demetrios Moschandreas | Illinois Institute of Technology (original) (raw)
Papers by Demetrios Moschandreas
Intelligent Buildings International
A relationship of building space conditioning energy and density of built-up area using street ge... more A relationship of building space conditioning energy and density of built-up area using street geometry as an urban design parameter was investigated in this study. Sixteen street geometry configurations with varying street width and orientation were investigated. A comparative energy analysis of a single, stand-alone eight-storey office building, with the same building as a part of urban building configuration, is presented. The sensitivity of microclimatic changes of increased air temperature and reduced wind speed was investigated for the building energy need of a compact street geometry. Additionally, the role of improved wall and roof surface albedo values on energy needs was studied in the urban context. The street geometry significantly influences the space conditioning energy of an urban building. The summertime cooling load of a code rated energy efficient building is reduced by up to 37% whereas heating loads are penalized by 19% by the studied street aspect ratio of 8. Ho...
Journal of the Human-Environment System, 2008
International Journal of Environment and Sustainable Development, 2008
ABSTRACT The aim of this study is to assess the performance of sustainable buildings. Its objecti... more ABSTRACT The aim of this study is to assess the performance of sustainable buildings. Its objective is to compare certified green buildings with similar in location, size, age and function conventional buildings by testing hypotheses that green buildings perform better than conventional ones. Objective data including building costs, energy and water consumption, material recycling, indoor pollution sources and proximity to public transportation and subjective information on occupant comfort, recycling systems and indoor pollution conditions were gathered by interviews of occupants and engineers of 20 buildings, the 10 certified sustainable buildings in the study area and 10 conventional buildings. Criteria for sustainable performance are (1) the five LEED certification components (2) 39 sustainability performance characteristics or attributes, at least seven within each component. Analyses with non-parametric tests indicate that there is no statistically significant difference between sustainable and conventional buildings in 49% of the attributes. Conventional buildings perform statistically better in 10% of the attributes examined. Green buildings perform better than conventional buildings for the remaining 39% of building performance attributes. We conclude that labelling buildings as sustainable, making use of design and construction plans does not guarantee sustainable building performance and recommend periodic performance evaluation of certified buildings.
Journal of Exposure Analysis and Environmental Epidemiology
Data are presented from a 24-month comprehensive study of the air quality in indoor non-industria... more Data are presented from a 24-month comprehensive study of the air quality in indoor non-industrial environments. A nine-month field study in the Boston metropolitan area monitored and compared indoor and outdoor air quality at ten residences and two office buildings. Seasonal variations were investigated under real-life conditions. Residences were classified as having indoor sources (gas facilities) or lacking indoor sources (electric facilities). Sulfur dioxide and ozone concentrations were consistently higher outdoors while indoor levels of nonmethane hydrocarbons and carbon dioxide were consistently higher. In general, indoor concentrations of carbon monoxide, nitric oxide, and nitrogen dioxide are greater than corresponding outdoor levels in residences with gas facilities. The indoor concentrations of CO, NO and NO/sub 2/ in residences with electric facilities are similar to outdoor levels. Indoor office concentrations of CO, NO and NO/sub 2/ usually track outdoor levels. Concen...
Journal of Hazardous Materials, 2008
Total trihalomethanes (TTHM) concentrations vary widely and periodically between 70 and 130 ppb. ... more Total trihalomethanes (TTHM) concentrations vary widely and periodically between 70 and 130 ppb. Data from the National Environmental Services Laboratory, Houston, Texas indicate that pH and free residual chlorine contribute minimally to the wide variability of TTHM levels. Temperature variation in drinking fluctuates from 11 to 27 degrees C. The objective of this research is to formulate a model that delineates more clearly the daily variations of the most prevalent volatile trihalomethane by-products: chloroform (CHCl3), bromodichloromethane (CHBr2Cl), and bromoform (CHBr3) levels from drinking water. This model simulates the daily fluctuation of THM at a single location and at any time during the day as a function of the water temperature and the average concentration of TTHM, which can be estimated. The hypothesis of this study is that observed daily fluctuations of TTHM, CHCl3, CHCl2Br, CHClBr2, and CHBr3 are periodic. This hypothesis is tested using autocorrelation functions and it is shown that for the series of pH the correlation coefficient is maximal at zero lags, rapidly decreases to zero, and increases again between 4- and 6-h period. Such pattern suggests random fluctuation unrelated to time. However, the series of free residual chlorine, temperature, TTHM, CHCl3, CHCl2Br, CHClBr2, and CHBr3 suggest a different pattern. The correlation coefficient increases when the time-shift approaches 24 h. These repetitions in fluctuation of content over a 24-h period are statistically significant. The model formulated in this study provides insights in TTHM variation and is a necessary tool to reduce the error when estimating potential risk from exposure to trihalomethane compounds in drinking water system. In general, calculation of potential risk by using a value measured early morning or late afternoon concentrations were found minimal lead to an underestimation of the population risk.
Journal of Exposure Analysis and Environmental Epidemiology, 2003
Journal of Exposure Analysis and Environmental Epidemiology, 2002
This paper identifies and ranks food items by estimating their contribution to the dietary exposu... more This paper identifies and ranks food items by estimating their contribution to the dietary exposure of the US population and 19 subpopulation groups. Contributions to dietary exposures to arsenic, cadmium, chromium, lead, nickel, benzene, chlorpyrifos, and diazinon are estimated using either the Dietary Exposure Potential Model (DEPM) approach, the National Human Exposure Assessment Survey Arizona (NHEXAS-AZ) approach or the combination of the two. The DEPM is a computer model that uses several national databases of food consumption and residue concentrations for estimating dietary. The DEPM approach ranks the contribution of food items to the total dietary exposure using two methods, the direct method that ranks contributions by population exposure magnitude and the weighted method that ranks by subpopulation exposure magnitude. The DEPM approach identifies highly exposed subpopulations and a relatively small number of food items contributing the most to dietary exposure. The NHEXAS-AZ approach uses the NHEXAS-AZ database containing food consumption data for each subject and chemical residues of a composite of food items consumed by each subject in 1 day during the sampling week. These data are then modeled to obtain estimates of dietary exposure to chemical residues. The third approach uses the NHEXAS-AZ consumption data with residue values from the national residue database. This approach also estimates percent contributions to exposure of each ranked food item for the Arizona population. Dietary exposures estimated using the three approaches are compared. The DEPM results indicate groups with highest dietary exposures include Nonnursing Infants, Children 1-6, Hispanic, Non-Hispanic White, Western, Northeast and Poverty 0-130%. The use of the Combined National Residue Database (CNRD) identifies 43 food items as primary contributors to total dietary exposure; they contribute a minimum of 68% of the total dietary exposure to each of the eight chemical residues. The percent contribution of ranked food items estimated using the NHEXAS samples is smaller than those obtained from the western US population via the DEPM. This indicates differences in consumption characteristics of the two groups with respect to the ranked food items. Six of 15 food items consumed by the NHEXAS-AZ subjects per day are ranked food items contributing between 56% and 70% of the estimated NHEXAS-AZ dietary exposure to each of the eight chemical residues. The difference between total dietary exposure estimates from the DEPM and NHEXAS-AZ approaches varies by chemical residue and is attributable to differences in sampling and analytical methods, and geographic areas represented by the data. Most metal exposures estimated using the NHEXAS consumption data with the CNRD have lower values than those estimated via the other approaches, possibly because the NHEXAS-AZ residue values are higher than the CNRD values. In addition, exposure estimates are seemingly affected by the difference in demographic characteristics and factors that affect types and amounts of food consumed. Efficient control strategies for reducing dietary exposure to chemical residues may be designed by focusing on the relatively small number of food items having similar ingredients that contribute substantively to the total ingestion exposure.
Journal of Exposure Analysis and Environmental Epidemiology, 2001
This paper formulates regression models and examines their ability to associate exposures to chlo... more This paper formulates regression models and examines their ability to associate exposures to chlorpyrifos and diazinon in residences with information obtained from questionnaires and environmental sampling of the National Human Exposure Assessment Survey Arizona (NHEXAS-AZ) database. A knowledge-based list of 29 potential exposure determinants was assembled from information obtained from six questionnaires administered in the course of the study. This list was used to select the independent variables of each model statistically and electronically. Depending on the data type of dependent and independent variables, four classes of regression models were developed to determine desired associations. Route-specific exposures were estimated using the indirect method of exposure estimation and measurements from the NHEXAS-AZ field study. The stepwise procedure was used to construct regression models. Significance level at P=0.10 was used for entry and retention of independent variables in a model. Twelve significant regression models were formulated to quantify associations among exposures and other variables in the NHEXAS-AZ database. Route-specific exposures to pesticides associate significantly with questionnaire-based variables such as preparation of pesticides, use of pesticide inside the house, and income level; and with concentration variables in three media: dermal wipe, sill wipe, and indoor air. Models formulated in this study may be used to estimate exposures to each of the pesticides. Yet, the use of these models must incorporate clear statements of the assumptions made in the formulation as well as the coefficient of determination and the confidence and prediction intervals of the dependent variable.
Journal of Environmental Science and Health, Part A, 2006
Conventional approaches to characterize and model the formation of trihalomethanes (THM) species ... more Conventional approaches to characterize and model the formation of trihalomethanes (THM) species in the distribution system use either residence time or water temperature. A significant deviation of THM levels were observed at the beginning and the end of a selected distribution system in Ontario, which may be because the consumption rate of residual chlorine is not constant in the distribution system. The approach developed in this study incorporates water temperature and proceeds with a trend and decomposition modeling method to incorporate the traveled distance and to explain the seasonal THM variation in the distribution system. The model has been tested and verified using a database from the Bettravia distribution system in Ontario, Canada. The deviations at the extremes of the distribution system were minimized due to the modeling technique used to develop the model and by including more factors that affect THM formation in the distribution system. The agreement between predicted and measured THM values at the beginning and the end of the distribution system is pronounced. The model presented in this paper is a robust tool that may be used by SDWAA to evaluate regulatory options and justify potential regulations regarding THM levels of the drinking water distribution system.
Journal of Environmental Science and Health, Part A, 2006
The premise of this study is that the presence of bromide has a substantial effect on both the sp... more The premise of this study is that the presence of bromide has a substantial effect on both the speciation and total formation of trihalomethane (THM). Consequently, models of water containing substantial bromide concentrations require refinement because they are only calibrated with raw water with high humic acid content. This study investigates and reports efforts on such refinement. The objectives of work reported in this paper are to formulate and validate a new correlative model that is based on physical principles and incorporates high levels of bromide that affect THM formation using raw water rich in both humic and fulvic acid. Two types of THM precursors are considered in the model discussed in this paper: (1) activated aromatic groups, which are more reactive with chlorine than with bromine, and (2) aliphatic groups, which are more reactive with bromine than with chlorine. Aliphatic and aromatic carbons are incorporated in the model by the inclusion of pertinent variables such as C/N and Br/Cl2 in the algorithm. The model also includes NH4+. This variable affects chlorine consumption that, in turn, potentially affects THM formation. For the first time ever, organic carbon to organic nitrogen and bromide to chlorine ratios is also used as variables potentially affecting THM formation when treating drinking water. The THM model formulated in this paper is an empirical model based on scientific principles and not simply a regression equation. The formulated model is pronounced valid based on a validation effort that employs a portion of an EPA database that was not used for model formulation.
Journal of Environmental Engineering, 2003
The research reported in this paper investigates the ability of a portable UV-based control devic... more The research reported in this paper investigates the ability of a portable UV-based control device (sizeϭ21 in.ϫ12 in. ϫ12 in.) to reduce airborne indoor bacteria levels to at or below outdoor ambient levels. Under controlled conditions, laboratory scale chamber (sizeϭ48 in.ϫ36 in.ϫ48 in.) experiments and field scale residence experiments were conducted using the UV control device. Pure cultures of Staphylococcus aureus were grown in culture media and atomized into bioaerosols in the laboratory chamber. The airborne levels of the bacteria were sampled using a six-stage Andersen sampler containing selective culture media plates, and the levels were counted as number of colony forming units per cubic meter of air. The UV control device reduced the atomizer-generated laboratory chamber Staphylococcus aureus levels from a range of 5,000-15,000 cfu/m 3 to below 120 cfu/m 3 within a 2 h period. Continuous operation of the UV control device in the bedroom and bathroom of a single-resident apartment reduced the Staphylococcus aureus counts from a range of 200-1,300 to less than 200 cfu/m 3 . The unit cost of the prototype UV control device is estimated at 120,andtheoperatingcostisestimatedat120, and the operating cost is estimated at 120,andtheoperatingcostisestimatedat0.74/day.
Journal of Environmental Engineering, 2001
ABSTRACT
International Journal of Risk Assessment and Management, 2005
ABSTRACT Risk assessment is a multi-disciplinary endeavour that synthesises scientific, social an... more ABSTRACT Risk assessment is a multi-disciplinary endeavour that synthesises scientific, social and economic factors and protects public health and natural resources. This paper assesses the literature and discerns the impact of risk uncertainty on human risk assessment, risk management and risk communication. This literature assessment is illustrative rather than comprehensive and regards risk assessment from the point of view of the environmental engineer. This paper puts forward exposure, dose and risk models used to estimate carcinogenic and non-carcinogenic deterministic (point estimates) or probabilistic risk and uncertainty values. The emphasis is on the uncertainty of risk estimates, uncertainty taxonomy and estimation of parameter uncertainty and uncertainty associated with selection of models and scenarios of exposure. This paper attempts to assess the current scientific schism among proponents of deterministic risk estimation and supporters of probabilistic risk and uncertainty estimates and asserts that either may be used as a factor of the risk assessment objectives and available data.
Environment International, 1982
A spatial comparison of pollutant concentrations within the residential environment is undertaken... more A spatial comparison of pollutant concentrations within the residential environment is undertaken, comparing pollutant concentrations from three indoor sampling locations (zones). The indoor air quality base was obtained from sampling the indoor air of 12 residential sites and two office buildings in the metropolitan Boston area. Each residential site was monitored continuously for two weeks, and data were reduced into hourly averages. Interzonal comparisons of the mean of hourly averages, 24-h averages, and daily maximum hourly concentrations were made at all sites. Linear regressions were computed between daily maximum hourly concentrations and mean 24-h concentrations of NO, NO2, and CO for kitchens to determine whether maximum hourly concentrations could be predicted from the 24-h concentration. These pollutants show interzonal statistical differences in residences with gas-fired cooking facilities but not in residences with electric cooking facilities. It was determined that, while one indoor sampling zone is not sufficient to specify indoor pollutant concentration maxima in residences having indoor sources of pollution, the daily mean of hourly pollutant concentrations obtained from one indoor zone can adequately describe the indoor environment. In addition, the maximum indoor hourly concentration for NO, NO2, and CO can be estimated for residences with all electric facilities, by using the mean 24-h concentration. The reliability of similar estimates for NO, NO2, and CO in residences with unvented gas appliances is reduced because of substantially more scatter in the paired data point, particularly at higher pollutant concentrations.
Environment International, 2002
The recently developed concepts of aggregate risk and cumulative risk rectify two limitations ass... more The recently developed concepts of aggregate risk and cumulative risk rectify two limitations associated with the classical risk assessment paradigm established in the early 1980s. Aggregate exposure denotes the amount of one pollutant available at the biological exchange boundaries from multiple routes of exposure. Cumulative risk assessment is defined as an assessment of risk from the accumulation of a common toxic effect from all routes of exposure to multiple chemicals sharing a common mechanism of toxicity. Thus, cumulative risk constitutes an improvement over the classical risk paradigm, which treats exposures from multiple routes as independent events associated with each specific route. Risk assessors formulate complex models and identify many realistic scenarios of exposure that enable them to estimate risks from exposures to multiple pollutants and multiple routes. The increase in complexity of the risk assessment process is likely to increase risk uncertainty. Despite evidence that scenario and model uncertainty contribute to the overall uncertainty of cumulative risk estimates, present uncertainty analysis of risk estimates accounts only for parameter uncertainty and excludes model and scenario uncertainties. This paper provides a synopsis of the risk assessment evolution and associated uncertainty analysis methods. This evolution leads to the concept of the scenario -model -parameter (SMP) cumulative risk uncertainty analysis method. The SMP uncertainty analysis is a multiple step procedure that assesses uncertainty associated with the use of judiciously selected scenarios and models of exposure and risk. Ultimately, the SMP uncertainty analysis method compares risk uncertainty estimates determined using all three sources of uncertainty with conventional risk uncertainty estimates obtained using only the parameter source. An example of applying the SMP uncertainty analysis to cumulative risk estimates from exposures to two pesticides indicates that inclusion of scenario and model sources increases uncertainty of risk estimates relative to those estimated using only the parameter source. Changes in uncertainty magnitude may affect decisions made by risk managers. D
Environment International, 1980
Data from suburban residences in the Boston metropolitan area reveal a potential adverse impact o... more Data from suburban residences in the Boston metropolitan area reveal a potential adverse impact on indoor air quality from woodburning in woodstoves and fireplaces. Ambient pollutant concentrations at each residence were compared to corresponding pollutant levels indoors at three locations (kitchen, bedroom, and activity room). Individual gaseous pollutant samples were averaged on an hourly basis while 24-h integrated samples of particulate matter were obtained. Ten gaseous pollutants were sampled along with total suspended particulates (TSP). Chemical analyses further determined ten components of TSP including trace metals, benzo-a-pyrene (BaP), respirable suspended particulates (RSP), and water soluble sulfates and nitrates. Monitoring lasted two weeks at each residence and was conducted under occupied, real-life, conditions. Observed, elevated indoor concentrations of TSP, RSP, and BaP are attributed to woodburning. Data indicate that average indoor TSP concentrations during woodburning periods were about three times corresponding levels during nonwoodburning periods. The primary 24-h national ambient air quality standard (NAAQS) for TSP was exceeded once indoors during fireplace use, and the secondary, 24-h TSP NAAQS, was also exceeded indoors by RSP concentrations. Indoor BaP concentrations during woodstove use averaged five times more than during nonwoodburning periods. At this stage, results are only indicative, but the potential impact from elevated indoor concentrations of TSP, RSP, and BaP, attributed to woodburning, may have long-term health implications.
Building Research & Information, 2006
The Indoor Environmental Quality (IEQ) conceptual model is validated with an independent consulta... more The Indoor Environmental Quality (IEQ) conceptual model is validated with an independent consultant generated database that was not used for its formulation. The model uses the Indoor Environmental Index (IEI) to assess the IEQ and select among three management options. IEI values are either calculated using measured environmental variables or predicted by a simple linear regression model with the Percent of Occupants with Two or More Persistent Symptoms (POPS2) index as the independent variable. Responses to a questionnaire determine POPS2 values. The paper investigates if the predicted IEI values lead to the same IEQ management decisions as the expensive calculated IEI values. The null hypothesis is that there is no difference between predicted and calculated IEI values. The second objective examines the consultant effect on environmental stressor and IEI measurements by testing the null hypothesis of no difference among consultants. The difference between the calculated and predicted IEI values is not statistically significant and the inexpensive predicted values can be used for management purposes. The consultant effect on IEI values is statistically significant but interpreted to have no practical importance because it does not affect selection of management options. Consequently, it is argued that the conceptual model can be used as a proactive management tool that may be used to improve and maintain IEQ.Le modèle conceptuel IEQ (Qualité de l'environnement intérieur) est validé avec une base de données générée par un consultant indépendant; elle n'a pas été utilisée pour sa formulation. Le modèle utilise l'IEI (Indice de l'environnement intérieur) pour évaluer l'IEQ et sélectionner l'une des trois options de gestion. Les valeurs de l'IEI sont soit calculées en utilisant des variables environnementales mesurées, soit prédites par un simple modèle de régression linéaire avec, comme variable indépendante, l'indice POPS2 (Pourcentage d'occupants présentant des symptômes persistants). Les réponses à un questionnaire déterminent les valeurs POPS2. Cet article cherche à savoir si les valeurs IEI prédites conduisent aux mêmes décisions de gestion IEQ que les valeurs IEI calculées à grand frais. L'hypothèse de différence nulle est qu'il n'y a pas de différence entre les valeurs IEI prédites et calculées. Le second objectif examine l'effet ‘consultant’ sur l'agresseur environnemental et les mesures IEI en testant l'hypothèse de différence nulle entre les consultants. La différence entre les valeurs IEI calculées et prédites n'est pas significative sur le plan statistique et les valeurs prédites à moindre frais peuvent être utilisées à des fins de gestion. L'effet ‘consultant’ sur les valeurs IEI est significatif sur le plan statistique mais il est interprété de façon à n'avoir aucune importance pratique car il n'affecte pas le choix d'options de gestion. En conséquence, l'auteur avance que ce modèle conceptuel peut être utilisé comme outil de gestion proactive qui pourrait servir à améliorer et à maintenir l'IEQ.Mots clés: évaluation des bâtiments, comparaison de consultants, indices environnementaux, environnement intérieur, validation de modèle, symptômes de l'occupant, bureaux
Atmospheric Environment, 2001
ABSTRACT
Intelligent Buildings International
A relationship of building space conditioning energy and density of built-up area using street ge... more A relationship of building space conditioning energy and density of built-up area using street geometry as an urban design parameter was investigated in this study. Sixteen street geometry configurations with varying street width and orientation were investigated. A comparative energy analysis of a single, stand-alone eight-storey office building, with the same building as a part of urban building configuration, is presented. The sensitivity of microclimatic changes of increased air temperature and reduced wind speed was investigated for the building energy need of a compact street geometry. Additionally, the role of improved wall and roof surface albedo values on energy needs was studied in the urban context. The street geometry significantly influences the space conditioning energy of an urban building. The summertime cooling load of a code rated energy efficient building is reduced by up to 37% whereas heating loads are penalized by 19% by the studied street aspect ratio of 8. Ho...
Journal of the Human-Environment System, 2008
International Journal of Environment and Sustainable Development, 2008
ABSTRACT The aim of this study is to assess the performance of sustainable buildings. Its objecti... more ABSTRACT The aim of this study is to assess the performance of sustainable buildings. Its objective is to compare certified green buildings with similar in location, size, age and function conventional buildings by testing hypotheses that green buildings perform better than conventional ones. Objective data including building costs, energy and water consumption, material recycling, indoor pollution sources and proximity to public transportation and subjective information on occupant comfort, recycling systems and indoor pollution conditions were gathered by interviews of occupants and engineers of 20 buildings, the 10 certified sustainable buildings in the study area and 10 conventional buildings. Criteria for sustainable performance are (1) the five LEED certification components (2) 39 sustainability performance characteristics or attributes, at least seven within each component. Analyses with non-parametric tests indicate that there is no statistically significant difference between sustainable and conventional buildings in 49% of the attributes. Conventional buildings perform statistically better in 10% of the attributes examined. Green buildings perform better than conventional buildings for the remaining 39% of building performance attributes. We conclude that labelling buildings as sustainable, making use of design and construction plans does not guarantee sustainable building performance and recommend periodic performance evaluation of certified buildings.
Journal of Exposure Analysis and Environmental Epidemiology
Data are presented from a 24-month comprehensive study of the air quality in indoor non-industria... more Data are presented from a 24-month comprehensive study of the air quality in indoor non-industrial environments. A nine-month field study in the Boston metropolitan area monitored and compared indoor and outdoor air quality at ten residences and two office buildings. Seasonal variations were investigated under real-life conditions. Residences were classified as having indoor sources (gas facilities) or lacking indoor sources (electric facilities). Sulfur dioxide and ozone concentrations were consistently higher outdoors while indoor levels of nonmethane hydrocarbons and carbon dioxide were consistently higher. In general, indoor concentrations of carbon monoxide, nitric oxide, and nitrogen dioxide are greater than corresponding outdoor levels in residences with gas facilities. The indoor concentrations of CO, NO and NO/sub 2/ in residences with electric facilities are similar to outdoor levels. Indoor office concentrations of CO, NO and NO/sub 2/ usually track outdoor levels. Concen...
Journal of Hazardous Materials, 2008
Total trihalomethanes (TTHM) concentrations vary widely and periodically between 70 and 130 ppb. ... more Total trihalomethanes (TTHM) concentrations vary widely and periodically between 70 and 130 ppb. Data from the National Environmental Services Laboratory, Houston, Texas indicate that pH and free residual chlorine contribute minimally to the wide variability of TTHM levels. Temperature variation in drinking fluctuates from 11 to 27 degrees C. The objective of this research is to formulate a model that delineates more clearly the daily variations of the most prevalent volatile trihalomethane by-products: chloroform (CHCl3), bromodichloromethane (CHBr2Cl), and bromoform (CHBr3) levels from drinking water. This model simulates the daily fluctuation of THM at a single location and at any time during the day as a function of the water temperature and the average concentration of TTHM, which can be estimated. The hypothesis of this study is that observed daily fluctuations of TTHM, CHCl3, CHCl2Br, CHClBr2, and CHBr3 are periodic. This hypothesis is tested using autocorrelation functions and it is shown that for the series of pH the correlation coefficient is maximal at zero lags, rapidly decreases to zero, and increases again between 4- and 6-h period. Such pattern suggests random fluctuation unrelated to time. However, the series of free residual chlorine, temperature, TTHM, CHCl3, CHCl2Br, CHClBr2, and CHBr3 suggest a different pattern. The correlation coefficient increases when the time-shift approaches 24 h. These repetitions in fluctuation of content over a 24-h period are statistically significant. The model formulated in this study provides insights in TTHM variation and is a necessary tool to reduce the error when estimating potential risk from exposure to trihalomethane compounds in drinking water system. In general, calculation of potential risk by using a value measured early morning or late afternoon concentrations were found minimal lead to an underestimation of the population risk.
Journal of Exposure Analysis and Environmental Epidemiology, 2003
Journal of Exposure Analysis and Environmental Epidemiology, 2002
This paper identifies and ranks food items by estimating their contribution to the dietary exposu... more This paper identifies and ranks food items by estimating their contribution to the dietary exposure of the US population and 19 subpopulation groups. Contributions to dietary exposures to arsenic, cadmium, chromium, lead, nickel, benzene, chlorpyrifos, and diazinon are estimated using either the Dietary Exposure Potential Model (DEPM) approach, the National Human Exposure Assessment Survey Arizona (NHEXAS-AZ) approach or the combination of the two. The DEPM is a computer model that uses several national databases of food consumption and residue concentrations for estimating dietary. The DEPM approach ranks the contribution of food items to the total dietary exposure using two methods, the direct method that ranks contributions by population exposure magnitude and the weighted method that ranks by subpopulation exposure magnitude. The DEPM approach identifies highly exposed subpopulations and a relatively small number of food items contributing the most to dietary exposure. The NHEXAS-AZ approach uses the NHEXAS-AZ database containing food consumption data for each subject and chemical residues of a composite of food items consumed by each subject in 1 day during the sampling week. These data are then modeled to obtain estimates of dietary exposure to chemical residues. The third approach uses the NHEXAS-AZ consumption data with residue values from the national residue database. This approach also estimates percent contributions to exposure of each ranked food item for the Arizona population. Dietary exposures estimated using the three approaches are compared. The DEPM results indicate groups with highest dietary exposures include Nonnursing Infants, Children 1-6, Hispanic, Non-Hispanic White, Western, Northeast and Poverty 0-130%. The use of the Combined National Residue Database (CNRD) identifies 43 food items as primary contributors to total dietary exposure; they contribute a minimum of 68% of the total dietary exposure to each of the eight chemical residues. The percent contribution of ranked food items estimated using the NHEXAS samples is smaller than those obtained from the western US population via the DEPM. This indicates differences in consumption characteristics of the two groups with respect to the ranked food items. Six of 15 food items consumed by the NHEXAS-AZ subjects per day are ranked food items contributing between 56% and 70% of the estimated NHEXAS-AZ dietary exposure to each of the eight chemical residues. The difference between total dietary exposure estimates from the DEPM and NHEXAS-AZ approaches varies by chemical residue and is attributable to differences in sampling and analytical methods, and geographic areas represented by the data. Most metal exposures estimated using the NHEXAS consumption data with the CNRD have lower values than those estimated via the other approaches, possibly because the NHEXAS-AZ residue values are higher than the CNRD values. In addition, exposure estimates are seemingly affected by the difference in demographic characteristics and factors that affect types and amounts of food consumed. Efficient control strategies for reducing dietary exposure to chemical residues may be designed by focusing on the relatively small number of food items having similar ingredients that contribute substantively to the total ingestion exposure.
Journal of Exposure Analysis and Environmental Epidemiology, 2001
This paper formulates regression models and examines their ability to associate exposures to chlo... more This paper formulates regression models and examines their ability to associate exposures to chlorpyrifos and diazinon in residences with information obtained from questionnaires and environmental sampling of the National Human Exposure Assessment Survey Arizona (NHEXAS-AZ) database. A knowledge-based list of 29 potential exposure determinants was assembled from information obtained from six questionnaires administered in the course of the study. This list was used to select the independent variables of each model statistically and electronically. Depending on the data type of dependent and independent variables, four classes of regression models were developed to determine desired associations. Route-specific exposures were estimated using the indirect method of exposure estimation and measurements from the NHEXAS-AZ field study. The stepwise procedure was used to construct regression models. Significance level at P=0.10 was used for entry and retention of independent variables in a model. Twelve significant regression models were formulated to quantify associations among exposures and other variables in the NHEXAS-AZ database. Route-specific exposures to pesticides associate significantly with questionnaire-based variables such as preparation of pesticides, use of pesticide inside the house, and income level; and with concentration variables in three media: dermal wipe, sill wipe, and indoor air. Models formulated in this study may be used to estimate exposures to each of the pesticides. Yet, the use of these models must incorporate clear statements of the assumptions made in the formulation as well as the coefficient of determination and the confidence and prediction intervals of the dependent variable.
Journal of Environmental Science and Health, Part A, 2006
Conventional approaches to characterize and model the formation of trihalomethanes (THM) species ... more Conventional approaches to characterize and model the formation of trihalomethanes (THM) species in the distribution system use either residence time or water temperature. A significant deviation of THM levels were observed at the beginning and the end of a selected distribution system in Ontario, which may be because the consumption rate of residual chlorine is not constant in the distribution system. The approach developed in this study incorporates water temperature and proceeds with a trend and decomposition modeling method to incorporate the traveled distance and to explain the seasonal THM variation in the distribution system. The model has been tested and verified using a database from the Bettravia distribution system in Ontario, Canada. The deviations at the extremes of the distribution system were minimized due to the modeling technique used to develop the model and by including more factors that affect THM formation in the distribution system. The agreement between predicted and measured THM values at the beginning and the end of the distribution system is pronounced. The model presented in this paper is a robust tool that may be used by SDWAA to evaluate regulatory options and justify potential regulations regarding THM levels of the drinking water distribution system.
Journal of Environmental Science and Health, Part A, 2006
The premise of this study is that the presence of bromide has a substantial effect on both the sp... more The premise of this study is that the presence of bromide has a substantial effect on both the speciation and total formation of trihalomethane (THM). Consequently, models of water containing substantial bromide concentrations require refinement because they are only calibrated with raw water with high humic acid content. This study investigates and reports efforts on such refinement. The objectives of work reported in this paper are to formulate and validate a new correlative model that is based on physical principles and incorporates high levels of bromide that affect THM formation using raw water rich in both humic and fulvic acid. Two types of THM precursors are considered in the model discussed in this paper: (1) activated aromatic groups, which are more reactive with chlorine than with bromine, and (2) aliphatic groups, which are more reactive with bromine than with chlorine. Aliphatic and aromatic carbons are incorporated in the model by the inclusion of pertinent variables such as C/N and Br/Cl2 in the algorithm. The model also includes NH4+. This variable affects chlorine consumption that, in turn, potentially affects THM formation. For the first time ever, organic carbon to organic nitrogen and bromide to chlorine ratios is also used as variables potentially affecting THM formation when treating drinking water. The THM model formulated in this paper is an empirical model based on scientific principles and not simply a regression equation. The formulated model is pronounced valid based on a validation effort that employs a portion of an EPA database that was not used for model formulation.
Journal of Environmental Engineering, 2003
The research reported in this paper investigates the ability of a portable UV-based control devic... more The research reported in this paper investigates the ability of a portable UV-based control device (sizeϭ21 in.ϫ12 in. ϫ12 in.) to reduce airborne indoor bacteria levels to at or below outdoor ambient levels. Under controlled conditions, laboratory scale chamber (sizeϭ48 in.ϫ36 in.ϫ48 in.) experiments and field scale residence experiments were conducted using the UV control device. Pure cultures of Staphylococcus aureus were grown in culture media and atomized into bioaerosols in the laboratory chamber. The airborne levels of the bacteria were sampled using a six-stage Andersen sampler containing selective culture media plates, and the levels were counted as number of colony forming units per cubic meter of air. The UV control device reduced the atomizer-generated laboratory chamber Staphylococcus aureus levels from a range of 5,000-15,000 cfu/m 3 to below 120 cfu/m 3 within a 2 h period. Continuous operation of the UV control device in the bedroom and bathroom of a single-resident apartment reduced the Staphylococcus aureus counts from a range of 200-1,300 to less than 200 cfu/m 3 . The unit cost of the prototype UV control device is estimated at 120,andtheoperatingcostisestimatedat120, and the operating cost is estimated at 120,andtheoperatingcostisestimatedat0.74/day.
Journal of Environmental Engineering, 2001
ABSTRACT
International Journal of Risk Assessment and Management, 2005
ABSTRACT Risk assessment is a multi-disciplinary endeavour that synthesises scientific, social an... more ABSTRACT Risk assessment is a multi-disciplinary endeavour that synthesises scientific, social and economic factors and protects public health and natural resources. This paper assesses the literature and discerns the impact of risk uncertainty on human risk assessment, risk management and risk communication. This literature assessment is illustrative rather than comprehensive and regards risk assessment from the point of view of the environmental engineer. This paper puts forward exposure, dose and risk models used to estimate carcinogenic and non-carcinogenic deterministic (point estimates) or probabilistic risk and uncertainty values. The emphasis is on the uncertainty of risk estimates, uncertainty taxonomy and estimation of parameter uncertainty and uncertainty associated with selection of models and scenarios of exposure. This paper attempts to assess the current scientific schism among proponents of deterministic risk estimation and supporters of probabilistic risk and uncertainty estimates and asserts that either may be used as a factor of the risk assessment objectives and available data.
Environment International, 1982
A spatial comparison of pollutant concentrations within the residential environment is undertaken... more A spatial comparison of pollutant concentrations within the residential environment is undertaken, comparing pollutant concentrations from three indoor sampling locations (zones). The indoor air quality base was obtained from sampling the indoor air of 12 residential sites and two office buildings in the metropolitan Boston area. Each residential site was monitored continuously for two weeks, and data were reduced into hourly averages. Interzonal comparisons of the mean of hourly averages, 24-h averages, and daily maximum hourly concentrations were made at all sites. Linear regressions were computed between daily maximum hourly concentrations and mean 24-h concentrations of NO, NO2, and CO for kitchens to determine whether maximum hourly concentrations could be predicted from the 24-h concentration. These pollutants show interzonal statistical differences in residences with gas-fired cooking facilities but not in residences with electric cooking facilities. It was determined that, while one indoor sampling zone is not sufficient to specify indoor pollutant concentration maxima in residences having indoor sources of pollution, the daily mean of hourly pollutant concentrations obtained from one indoor zone can adequately describe the indoor environment. In addition, the maximum indoor hourly concentration for NO, NO2, and CO can be estimated for residences with all electric facilities, by using the mean 24-h concentration. The reliability of similar estimates for NO, NO2, and CO in residences with unvented gas appliances is reduced because of substantially more scatter in the paired data point, particularly at higher pollutant concentrations.
Environment International, 2002
The recently developed concepts of aggregate risk and cumulative risk rectify two limitations ass... more The recently developed concepts of aggregate risk and cumulative risk rectify two limitations associated with the classical risk assessment paradigm established in the early 1980s. Aggregate exposure denotes the amount of one pollutant available at the biological exchange boundaries from multiple routes of exposure. Cumulative risk assessment is defined as an assessment of risk from the accumulation of a common toxic effect from all routes of exposure to multiple chemicals sharing a common mechanism of toxicity. Thus, cumulative risk constitutes an improvement over the classical risk paradigm, which treats exposures from multiple routes as independent events associated with each specific route. Risk assessors formulate complex models and identify many realistic scenarios of exposure that enable them to estimate risks from exposures to multiple pollutants and multiple routes. The increase in complexity of the risk assessment process is likely to increase risk uncertainty. Despite evidence that scenario and model uncertainty contribute to the overall uncertainty of cumulative risk estimates, present uncertainty analysis of risk estimates accounts only for parameter uncertainty and excludes model and scenario uncertainties. This paper provides a synopsis of the risk assessment evolution and associated uncertainty analysis methods. This evolution leads to the concept of the scenario -model -parameter (SMP) cumulative risk uncertainty analysis method. The SMP uncertainty analysis is a multiple step procedure that assesses uncertainty associated with the use of judiciously selected scenarios and models of exposure and risk. Ultimately, the SMP uncertainty analysis method compares risk uncertainty estimates determined using all three sources of uncertainty with conventional risk uncertainty estimates obtained using only the parameter source. An example of applying the SMP uncertainty analysis to cumulative risk estimates from exposures to two pesticides indicates that inclusion of scenario and model sources increases uncertainty of risk estimates relative to those estimated using only the parameter source. Changes in uncertainty magnitude may affect decisions made by risk managers. D
Environment International, 1980
Data from suburban residences in the Boston metropolitan area reveal a potential adverse impact o... more Data from suburban residences in the Boston metropolitan area reveal a potential adverse impact on indoor air quality from woodburning in woodstoves and fireplaces. Ambient pollutant concentrations at each residence were compared to corresponding pollutant levels indoors at three locations (kitchen, bedroom, and activity room). Individual gaseous pollutant samples were averaged on an hourly basis while 24-h integrated samples of particulate matter were obtained. Ten gaseous pollutants were sampled along with total suspended particulates (TSP). Chemical analyses further determined ten components of TSP including trace metals, benzo-a-pyrene (BaP), respirable suspended particulates (RSP), and water soluble sulfates and nitrates. Monitoring lasted two weeks at each residence and was conducted under occupied, real-life, conditions. Observed, elevated indoor concentrations of TSP, RSP, and BaP are attributed to woodburning. Data indicate that average indoor TSP concentrations during woodburning periods were about three times corresponding levels during nonwoodburning periods. The primary 24-h national ambient air quality standard (NAAQS) for TSP was exceeded once indoors during fireplace use, and the secondary, 24-h TSP NAAQS, was also exceeded indoors by RSP concentrations. Indoor BaP concentrations during woodstove use averaged five times more than during nonwoodburning periods. At this stage, results are only indicative, but the potential impact from elevated indoor concentrations of TSP, RSP, and BaP, attributed to woodburning, may have long-term health implications.
Building Research & Information, 2006
The Indoor Environmental Quality (IEQ) conceptual model is validated with an independent consulta... more The Indoor Environmental Quality (IEQ) conceptual model is validated with an independent consultant generated database that was not used for its formulation. The model uses the Indoor Environmental Index (IEI) to assess the IEQ and select among three management options. IEI values are either calculated using measured environmental variables or predicted by a simple linear regression model with the Percent of Occupants with Two or More Persistent Symptoms (POPS2) index as the independent variable. Responses to a questionnaire determine POPS2 values. The paper investigates if the predicted IEI values lead to the same IEQ management decisions as the expensive calculated IEI values. The null hypothesis is that there is no difference between predicted and calculated IEI values. The second objective examines the consultant effect on environmental stressor and IEI measurements by testing the null hypothesis of no difference among consultants. The difference between the calculated and predicted IEI values is not statistically significant and the inexpensive predicted values can be used for management purposes. The consultant effect on IEI values is statistically significant but interpreted to have no practical importance because it does not affect selection of management options. Consequently, it is argued that the conceptual model can be used as a proactive management tool that may be used to improve and maintain IEQ.Le modèle conceptuel IEQ (Qualité de l'environnement intérieur) est validé avec une base de données générée par un consultant indépendant; elle n'a pas été utilisée pour sa formulation. Le modèle utilise l'IEI (Indice de l'environnement intérieur) pour évaluer l'IEQ et sélectionner l'une des trois options de gestion. Les valeurs de l'IEI sont soit calculées en utilisant des variables environnementales mesurées, soit prédites par un simple modèle de régression linéaire avec, comme variable indépendante, l'indice POPS2 (Pourcentage d'occupants présentant des symptômes persistants). Les réponses à un questionnaire déterminent les valeurs POPS2. Cet article cherche à savoir si les valeurs IEI prédites conduisent aux mêmes décisions de gestion IEQ que les valeurs IEI calculées à grand frais. L'hypothèse de différence nulle est qu'il n'y a pas de différence entre les valeurs IEI prédites et calculées. Le second objectif examine l'effet ‘consultant’ sur l'agresseur environnemental et les mesures IEI en testant l'hypothèse de différence nulle entre les consultants. La différence entre les valeurs IEI calculées et prédites n'est pas significative sur le plan statistique et les valeurs prédites à moindre frais peuvent être utilisées à des fins de gestion. L'effet ‘consultant’ sur les valeurs IEI est significatif sur le plan statistique mais il est interprété de façon à n'avoir aucune importance pratique car il n'affecte pas le choix d'options de gestion. En conséquence, l'auteur avance que ce modèle conceptuel peut être utilisé comme outil de gestion proactive qui pourrait servir à améliorer et à maintenir l'IEQ.Mots clés: évaluation des bâtiments, comparaison de consultants, indices environnementaux, environnement intérieur, validation de modèle, symptômes de l'occupant, bureaux
Atmospheric Environment, 2001
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