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This digital document is a journal article from Science of the Total Environment, The, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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In this study, the potential exposure of bus commuters to significant air parameters (CO"2, CO and RSP) and thermal environment (air temperature and relative humidity) when buses traveled through tunnels in Hong Kong was investigated. It was found that air-conditioned buses provided a better commuting environment than non-air-conditioned buses. The blate increasing trend was found on air-conditioned buses as the in-bus air parameters concentration levels rose slowly throughout the traveling process. In contrast, the in-bus environment varied rapidly on non-air-conditioned buses as it depended on the out-bus environment. The measured in-bus CO concentration was 2.9 ppm on air-conditioned buses, while it was 4.6 ppm (even reaching the highest level at 12.0 ppm) on non-air-conditioned buses. Considering the in-bus thermal environment, air-conditioned buses provided thermally comfortable cabins (about 24 ^oC and 59% of relative humidity). However, on non-air-conditioned buses, the thermal environment varied with the out-bus environment. The mean in-bus air temperature was about 34 ^oC and 66% of relative humidity, and the in-bus air temperature varied between 29 and 38 ^oC. Also, the lower-deck to upper-deck air parameters concentration ratios indicated that the vertical dispersion of air pollutants in tunnels influenced non-air-conditioned buses as higher air parameters concentration levels were obtained on the lower-deck cabins. ... Read more

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This digital document is a journal article from Building and Environment, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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In Hong Kong, the Environmental Protection Department (HKEPD) has launched an indoor air quality (IAQ) certification scheme to promote an acceptable IAQ in workplaces. However, the associated uncertainties and measurement efforts have not been detailed for practical measurement in indoor spaces. In this study, indoor carbon dioxide (CO"2) concentration is selected as an indicator of the IAQ to investigate the probable errors and measurement efforts in different sampling schemes regarding the sampling point density. In particular, a one-year measurement for sample-spatial average indoor CO"2 concentration at 17 sampling locations in a typical large office (floor area=1200m^2) has been used to evaluate the probable errors of the sample-spatial average concentrations using different sampling point densities. The result shows that the measured concentration at a single sampling point could not be representative for the space and more than one sampling locations would be required in order to increase the measurement accuracy. Mathematical expressions for the sample-spatial average concentration at a confidence level at certain sampling point densities are proposed. When doubled the required measurement points, it was found that the probability of obtaining a measured CO"2 concentration at the confidence level of 95% could be increased from 70% to 90%, as compared with the current sampling practice. It is recommended to specify the measurement uncertainties in future codes so that effort for IAQ measurements in indoor spaces could be determined for practical strategies. ... Read more

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This digital document is an article from Northern Ontario Business, published by Laurentian Business Publishing, Inc. on January 1, 2003. The length of the article is 540 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser.

Citation Details
Title: Marathon Pulp investing in air quality. (Special Report: Energy/Environment).
Author: Gianni Ubriaco
Publication: Northern Ontario Business (Magazine/Journal)
Date: January 1, 2003
Publisher: Laurentian Business Publishing, Inc.
Volume: 23Issue: 3Page: 9(1)

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This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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High (episodic) particulate matter (PM) events over the sister cities of Douglas (AZ) and Agua Prieta (Sonora), located in the US-Mexico border, were simulated using the 3D Eulerian air quality model, MODELS-3/CMAQ. The best available input information was used for the simulations, with pollution inventory specified on a fine grid. In spite of inherent uncertainties associated with the emission inventory as well as the chemistry and meteorology of the air quality simulation tool, model evaluations showed acceptable PM predictions, while demonstrating the need for including the interaction between meteorology and emissions in an interactive mode in the model, a capability currently unavailable in MODELS-3/CMAQ when dealing with PM. Sensitivity studies on boundary influence indicate an insignificant regional (advection) contribution of PM to the study area. The contribution of secondary particles to the occurrence of high PM events was trivial. High PM episodes in the study area, therefore, are purely local events that largely depend on local meteorological conditions. The major PM emission sources were identified as vehicular activities on unpaved/paved roads and wind-blown dust. The results will be of immediate utility in devising PM mitigation strategies for the study area, which is one of the US EPA-designated non-attainment areas with respect to PM. ... Read more

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This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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A simple methodology was developed to collect measurements of duty cycle, the fraction of time the heating and air conditioning (HAC) system was operating, inside residences. The primary purpose of the measurements was to assess whether the HAC duty cycle was related to reductions in indoor particulate matter (PM) concentrations. A miniature temperature logger placed on an HAC outlet vent monitored changes in temperature as the system cooled or heated the residence. Temperature step changes signaling duty cycle periods were identified using spreadsheet macros. Parallel measurements of 24-h integrated air exchange rates (AERs) and indoor PM"2"."5 and PM"1"0 concentrations were collected to determine relationships with the duty cycle. The mild temperatures (mean=18.7^oC) present during the Spring season of the RTP PM Panel Study and personal comfort preferences caused low and variable daily duty cycles (mean=0.061, std. dev.=0.054) in both heating and cooling mode. Warmer ambient temperatures during the Fall season of the Tampa Asthmatic Children's Study (TACS) resulted in cooling-only HAC operation, with a higher mean duty cycle of 0.21 (std. dev.=0.11). Statistically significant linear relationships were observed between daily average duty cycle and the ambient temperature for both studies. Duty cycle exhibited a strong diurnal pattern commensurate with ambient temperature fluctuations. Duty cycles were positively associated with the residence AERs for heating-mode operations, but negatively associated when operating in cooling mode. Personal preferences contributed to the variability in the relationship between duty cycle and AER. The relationship between duty cycle and PM"2"."5 or PM"1"0 indoor-outdoor ratios were not statistically significant. The association of duty cycle with indoor-outdoor ratio was confounded by the short time span (mean of 10.3min for the TACS) of HAC system operation and the presence of strong indoor sources altering the indoor concentration levels. ... Read more

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This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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A multimedia mass balance model is described that has the potential to contribute to improved assessment of the levels and fate of volatile organic compounds (VOCs) in urban environments. It determines the fate and concentration of organic chemicals in the urban atmosphere under both steady-state and dynamic conditions. It can be used to estimate the fraction of the mass emitted that may participate in photochemical reactions leading to ozone formation, as distinct from the fraction which is dissipated by other processes. Five compartments are included: air (including aerosols), surface water, soil, vegetation and a non-polar organic urban film that coats impervious urban surfaces. Five test chemicals are assessed, viz. pentane, toluene, naphthalene, anthracene and pyrene, representing a range in volatility and atmospheric reactivity. The steady-state results suggest that the more volatile chemicals (pentane and toluene) remain almost entirely in the gaseous phase and advection and atmospheric reaction losses are the only important processes. For the less volatile chemicals, with liquid vapor pressures below a ''cut-off'' of approximately 10Pa, partitioning to other media increases, notably to soil and water, thus a lower fraction of the emitted mass reacts in the atmosphere and is a potential ozone precursor. The dynamic results show how changes in the hydroxyl radical (OH) concentrations and advection rates affect chemical fate. It is suggested that the model can contribute to improved assessment of the fate of a variety of organic chemicals in urban areas, especially if certain inter-media partitioning and transport parameters can be better quantified. ... Read more

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This digital document is an article from The Register-Guard (Eugene, OR), published by The Register Guard on November 1, 2003. The length of the article is 639 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser.

Citation Details
Title: Air quality forecast begins today.(Environment)(An agency's measurements mark the beginning of the wood burning season)
Publication: The Register-Guard (Eugene, OR) (Newspaper)
Date: November 1, 2003
Publisher: The Register Guard
Page: B1

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This digital document is a journal article from Building and Environment, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Currently, most local authorities in the UK use well-established Gaussian-type dispersion models to predict the air quality in urban areas. The use of computational fluid dynamics (CFD) in integrated urban air quality modelling is still in its infancy, despite having an enormous potential in assessing and improving natural ventilation in built-up areas. This study assesses the suitability of a general CFD code (PHOENICS) for use in integrated urban air quality modelling for regulatory purposes. An urban air quality model of a designated air quality management area in the city centre of Glasgow has been developed by integrating traffic flow data for urban road networks, traffic pollutant emission data and a three-dimensional CFD dispersion model of a complex configuration of street canyons. The results are in good agreement with field measurements taken during the continuous monitoring campaign, and show that a general CFD code has indeed the potential for regulatory use. Although this numerical tool has demonstrated satisfactory performance, it is observed that small differences in monitoring station positioning may yield significant variations of the measured mean concentration, due to large values of horizontal and vertical local concentration gradients. Although, at this stage, the accuracy of the developed Glasgow urban air quality model is highly dependent on the experience of its users, it is believed that use of a CFD code (such as PHOENICS) could benefit urban planners, architects, HVAC engineers and all other professionals interested in public health. ... Read more

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This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Over the next several years, grid-based photochemical models such as the community multiscale air quality (CMAQ) model, the regional modeling system for aerosols and deposition (REMSAD), the comprehensive air quality model with extensions (CAMx), and other regional models will be used by regulatory agencies in the United States for designing emission control strategies to meet and maintain the National Ambient Air Quality Standards (NAAQS) for O"3, PM"2"."5, and regional haze. In this study, temporal scale analysis is applied as a technique to evaluate an annual simulation of meteorology, O"3, and PM"2"."5 and its chemical components over the continental US utilizing two modeling systems. The spectral decomposition of total PM"2"."5 mass from hourly observations and CMAQ and REMSAD model predictions revealed that days of high PM"2"."5 concentrations are generally characterized by positive forcing from fluctuations having periods equal to or greater than a day (i.e., the diurnal, synoptic, and longer-term components) while the magnitude of intra-day fluctuations showed only small differences between average and episodic conditions. Both modeling systems did not capture most of the variability of the high-frequency, intra-day component for all variables for which hourly measurements were available. Furthermore, it is illustrated that correlations were insignificant on the intra-day time scale for all variables, suggesting that these models in the setup used for this study were not skillful in simulating the higher-frequency variations in meteorological variables and the levels of all pollutants. The models exhibited greatest skills at capturing longer-term (seasonal) fluctuations for temperature, wind speed, O"3, sulfate and nitrate. Correlations for total PM"2"."5, ammonium, elemental carbon (EC), organic carbon (OC) and crustal PM"2"."5 correlations were highest for the synoptic time scale implying problems with factors other than meteorology, such as emissions or lateral chemical boundary conditions, in capturing the baseline fluctuations. ... Read more

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This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Local NO"2 concentrations near Rotterdam (Netherlands) were assessed for the year 2010, focusing on the uncertainties and the changes in exceedance of European air quality standards. In the first step of the 2-step assessment method, the background contribution was determined by error-in-variable external drift kriging, where measurements and dispersion model output in the 1987-2003 period were combined. The result was subsequently extrapolated using dispersion model output and an emission scenario for 2010. In the second step, the local traffic contribution was added on the basis of a local generic dispersion model with use of an emission scenario for 2010. This resulted in maps showing local NO"2 concentrations, upper and lower limits, and probabilities of exceeding the 40@mgm^-^3 air quality standard. The probabilistic measures were calculated in numbers and translated into words for easier communication. Using this method and scenario we found that within about 100m from the highways near Rotterdam the mean NO"2 concentrations are likely to exceed the standard in 2010. The chance of exceeding the standard is unlikely up to 1km from the highways, where the mean is expected to be below the standard in 2010. ... Read more

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This digital document is an article from Industrial Environment, published by Thomson Gale on November 1, 2005. The length of the article is 627 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser.

Citation Details
Title: BNSF RAILWAY SHOWCASES TECHNOLOGY FOR CLEANER AIR QUALITY.
Publication: Industrial Environment (Magazine/Journal)
Date: November 1, 2005
Publisher: Thomson Gale
Volume: 16Issue: 11Page: NA

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Product Description
This digital document is a journal article from Environment International, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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With both climate change and air quality on political and social agendas from local to global scale, the links between these hitherto separate fields are becoming more apparent. Black carbon, largely from combustion processes, scatters and absorbs incoming solar radiation, contributes to poor air quality and induces respiratory and cardiovascular problems. Uncertainties in the amount, location, size and shape of atmospheric black carbon cause large uncertainty in both climate change estimates and toxicology studies alike. Increased research has led to new effects and areas of uncertainty being uncovered. Here we draw together recent results and explore the increasing opportunities for synergistic research that will lead to improved confidence in the impact of black carbon on climate change, air quality and human health. Topics of mutual interest include better information on spatial distribution, size, mixing state and measuring and monitoring. ... Read more

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This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Essential oils, predominantly comprised of a group of aromatic chemicals, have attracted increasing attention as they are introduced into indoor environments through various forms of consumer products via different venues. Our study aimed to characterize the profiles and concentrations of emitted volatile organic compounds (VOCs) when evaporating essential oils indoors. Three popular essential oils in the market, lavender, eucalyptus, and tea tree, based on a nation-wide questionnaire survey, were tested. Specific aromatic compounds of interest were sampled during evaporating the essential oils, and analyzed by GC-MS. Indoor carbon monoxide (CO), carbon dioxide (CO"2), total volatile organic compounds (TVOCs), and particulate matters (PM"1"0) were measured by real-time, continuous monitors, and duplicate samples for airborne fungi and bacteria were collected in different periods of the evaporation. Indoor CO (average concentration 1.48 vs. 0.47ppm at test vs. background), CO"2 (543.21 vs. 435.47ppm), and TVOCs (0.74 vs. 0.48ppm) levels have increased significantly after evaporating essential oils, but not the PM"1"0 (2.45 vs. 2.42ppm). The anti-microbial activity on airborne microbes, an effect claimed by the use of many essential oils, could only be found at the first 30-60min after the evaporation began as the highest levels of volatile components in these essential oils appeared to emit into the air, especially in the case of tea tree oil. High emissions of linalool (0.092-0.787mgm^-^3), eucalyptol (0.007-0.856mgm^-^3), d-limonene (0.004-0.153mgm^-^3), @r-cymene (0.019-0.141mgm^-^3), and terpinene-4-ol-1 (0.029-0.978mgm^-^3), all from the family of terpenes, were observed, and warranted for further examination for their health implications, especially for their potential contribution to the increasing indoor levels of secondary pollutants such as formaldehyde and secondary organic aerosols (SOAs) in the presence of ozone. ... Read more

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This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Advances in satellite sensors have provided new datasets for monitoring air quality at urban and regional scales. Qualitative true color images and quantitative aerosol optical depth data from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on the Terra satellite were compared with ground-based particulate matter data from US Environmental Protection Agency (EPA) monitoring networks covering the period from 1 April to 30 September, 2002. Using both imagery and statistical analysis, satellite data enabled the determination of the regional sources of air pollution events, the general type of pollutant (smoke, haze, dust), the intensity of the events, and their motion. Very high and very low aerosol optical depths were found to be eliminated by the algorithm used to calculate the MODIS aerosol optical depth data. Correlations of MODIS aerosol optical depth with ground-based particulate matter were better in the eastern and Midwest portion of the United States (east of 100^oW). Data were patchy and had poorer correlations in the western US, although the correlation was dependent on location. This variability is likely due to a combination of the differences between ground-based and column average datasets, regression artifacts, variability of terrain, and MODIS cloud mask and aerosol optical depth algorithms. Preliminary analysis of the algorithms indicated that aerosol optical depth measurements calculated from the sulfate-rich aerosol model may be more useful in predicting ground-based particulate matter levels, but further analysis would be required to verify the effect of the model on correlations. Overall, the use of satellite sensor data such as from MODIS has significant potential to enhance air quality monitoring over synoptic and regional scales. ... Read more

Product Description
This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Meteorological models in conjunction with air quality models are being used to simulate the transport and fate of pollutants in the atmosphere. Hence, there is a need for an extensive evaluation of the entire modeling system. In this study, several new techniques to assess the performance of mesoscale meteorological models are introduced with an emphasis on evaluating the variables and processes that have the potential to influence the air quality predictions, since errors in the meteorological fields are passed on to the air quality model. Model performance was diagnosed by examining the inter-correlation of observable variables in the atmosphere on distinct time scales: intraday, diurnal, and synoptic. It was found that the Mesoscale Model version 5 (MM5) model did replicate the observed relationship between intraday wind speed and temperature, intraday surface pressure and temperature, diurnal surface pressure and temperature as well as most of the correlations between variables on the synoptic timescale. However, a negative correlation between temperature and precipitation was evident in the observations on the intraday scale, but such relationship was not evident in the model output. Furthermore, the diurnal response of increasing wind speed with temperature was strong in the observed time series, but it was much weaker in the model. The correlation between diurnal changes in temperature and cloud fraction was consistently negative in the model whereas it was slightly positive in the observations. Wind profilers were used to examine the simulated boundary layer wind structure. Of the twelve sites examined, the average distance error between the 24-h observed and modeled trajectory was approximately 150km at height of 100m above the surface. Errors in transport of this magnitude (100-200km) can produce errors in air quality predictions. It is not the intent of this study to establish quantitative links between the performance of the specific meteorological simulation analyzed here and subsequent air quality simulations. Rather, the results presented here draw attention to errors and inconsistencies in the meteorology that are passed on to the air quality model which, in turn, have the potential to cause errors in air quality model predictions. ... Read more

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This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Isoprene fluxes from a Salix viminalis (willow) plantation in western Sweden were measured using the relaxed eddy accumulation (REA) technique. Fluxes of up to 0.23@mgm^-^2s^-^1 could be observed. A standard emission factor at 303K and a PAR flux of 1000@mmolm^-^2 s^-^1 was estimated to 0.98@mgm^-^2s^-^1 by using the G93 algorithm. The chemistry of an air parcel passing over a willow coppice plantation was investigated utilising a Lagrangian box model in which the measured isoprene fluxes were used as input data. Dispersion after the field was accounted for by a procedure based on the Gaussian plume model. The calculations indicate that, in most cases, the isoprene emissions have a small effect on the local air quality. ... Read more

Product Description
This digital document is a journal article from Building and Environment, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Continuous sampling is one of the common approaches for assessing indoor pollutant level. It is believed that the longer the measurement time, the higher the accuracy and confidence level of the measurement can be achieved. In 2003, the Hong Kong Environmental Protection Department (HKEPD) launched an Indoor Air Quality (IAQ) certification scheme to promote an acceptable IAQ in workplaces. However, measurement efforts and uncertainties associated with the sampling method have not been addressed. Alternative sampling schemes taking shorter measurements in the sampling period were proposed in some circumstances. In this study, the average carbon dioxide (CO"2) concentration of a workplace is selected as an indicator of the indoor air quality to investigate the probable errors and measurement efforts in four sampling schemes, regarding the sampling period: in Scheme A, it is from a continuous sampling throughout the measurement; in Scheme B, it is from two sampling periods of two equal sessions of the measurement; in Scheme C, it is from two structural sampling periods of the two sessions; and in Scheme D, the average concentration is from four sampling periods in four equal sessions of the measurement. In particular, a year-round indoor CO"2 concentration at 17 locations in a typical office in Hong Kong was used to evaluate the probable errors using these four sampling schemes. At certain confidence levels, the required measurement times of the alternative sampling schemes (Schemes B, C, D) were evaluated and compared with that of an 8-hour continuous one (Scheme A). It was found that Scheme C would offer a reduction of measurement effort up to 30%. It is recommended to specify the uncertainties and efforts of measurement in future codes, and to consider these sampling schemes in determining practical strategies for IAQ measurement. ... Read more

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This volume is produced from digital images created through the University of Michigan University Library's large-scale digitization efforts. The Library seeks to preserve the intellectual content of items in a manner that facilitates and promotes a variety of uses. The digital reformatting process results in an electronic version of the original text that can be both accessed online and used to create new print copies. The Library also understands and values the usefulness of print and makes reprints available to the public whenever possible. This book and hundreds of thousands of others can be found in the HathiTrust, an archive of the digitized collections of many great research libraries. For access to the University of Michigan Library's digital collections, please see http://www.lib.umich.edu and for information about the HathiTrust, please visit http://www.hathitrust.org ... Read more