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All experiments were carried out in a prototype vortexing fluidized bed combustor (VFBC). The dimension of the combustion chamber is 0.7 x 1.4 x 2 m, and the freeboard section is 1 m i.d. and 4 m in height. Paper sludge was used as the feeding material. Two types of coal particles were employed as the supplementary fuel. In order to understand the characteristics of the VFBC system for paper sludge incineration, the effect of various operating parameters, such as the primary airflow, excess air ratio, and secondary airflow rates, on temperature distribution, ash elutriation, combustion efficiency, and pollutant emissions were investigated. [ABSTRACT FROM AUTHOR]

Evaluates the potential for reducing indoor styrene exposure from copied paper through use of low-emitting toners. determination of air-borne styrene emission rates from freshly copied paper; Impact of lower-styrene toners on emissions from the copier; Generalization of the results of the above-mentioned experiment.

Transportation-related emissions are the dominant contributing source of air pollutants today. Considering the negative impacts of transportation-related emissions on our social and economic environment, extensive efforts have been made by researchers and practitioners attempting to find solutions to reduce the emissions. To synthesize these research efforts, researchers have conducted various reviews of relevant studies. However, because of the diversity of the topics, most of existing reviews have only focused on specific and narrowed areas. Furthermore, none of the existing reviews have attempted to summarize the researchers' opinions on the current research and their prospects of the future research directions. Therefore, this paper is intended to fill this gap by conducting an extensive survey of transportation emissions professionals. In the paper, a review of existing research and developments on each of the emissionsrelated topics is provided, followed by a presentation of the respective survey results and analysis. At the conclusion of these reviews and the analysis of the survey, some future research directions in this field are presented. [ABSTRACT FROM AUTHOR]

Weather condition is one of the most important factors affecting spatial and temporal distributions of air pollutants, especially for short-term air dispersion. Abnormal weather conditions might lead to higher or lower ambient air concentrations than they would be under normal weather conditions. Therefore, testing for normality of weather conditions during the air monitoring period is an essential step for evaluating ambient air monitoring results. In this paper, a distance method was used to select a most representative weather station from the available candidates. An array of meteorological elements were identified that affect air dispersion and transportation. A statistical method was used to determine whether the weather conditions during the air monitoring period were significantly different from that of previous years. Using methyl bromide ambient air monitoring as a case study, this paper documents the methods, procedures, and results of weather analysis for Monterey, Santa Cruz, and Kern Counties during ambient air monitoring periods for methyl bromide in the year 2000. With a few exceptions, the meteorological elements and atmospheric stability factors, such as wind speeds, wind directions, and stability classes, during the monitoring period were in the normal range. Although there were higher frequencies of stable atmospheric conditions in Monterey/Santa Cruz Counties than in Kern County, weather conditions during the monitoring period were not significantly different from normal local weather conditions of previous years. Consequently, the subchronic air concentrations observed during the ambient air monitoring periods for methyl bromide in the year 2000 was taken under typical weather conditions of those areas at that time of the year. [ABSTRACT FROM AUTHOR]

In December 1994, the South Coast Air Quality Management District (SCAQMD) initiated a comprehensive program, the PM[sub10] Technical Enhancement Program (PTEP), to characterize fine PM in the South Coast Air Basin (SCAB). A 1-year special particulate monitoring project was conducted from January 1995 to February 1996 as part of the PTEP. Under this enhanced monitoring, HNO[sub3], NH[sub3], and speciated PM[sub10] and PM[sub2.5] concentrations were measured at five stations (Anaheim, downtown Los Angeles, Diamond Bar, Fontana, and Rubidoux) in the SCAB and at one background station at San Nicolas Island. PM[sub2.5] and PM[sub10] mass and 43 individual species were analyzed for a full chemical speciation of the particle data. The PTEP data indicate that the most abundant chemical components of PM[sub10] and PM[sub2.5] in the SCAB are NH[ sub4, sup+] (8-9% of PM[sub10] and 14-17% of PM[sub2.5]), NO[sub3,sup-] (23-26% of PM[sub10] and 28-41% of PM[sub2.5]), SO[sub4](6-11% of PM[sub10] and 9-18% of PM[sub2.5]), organic carbon (OC) (15-19% of PM[sub10] and 18-26% of PM[sub2.5]), and elemental carbon (EC) (5-8% of PM[sub10] and 8-13% of PM[sub2.5]). On an annual average basis, PM[sub2.5] comprises 52-59% of the SCAB PM[sub10]. Annual average PM[sub10] and PM[sub2.5] concentrations showed strong spatial variations, low at coastal sites and high at inland sites. Annual average PM[sub10] concentrations varied from 40.8 µg/m³ at Anaheim to 76.8 µg/m³ at Rubidoux, while annual average PM[sub2.5] concentrations varied from 21.7 µg/m³ at Anaheim to 39.8 µg/m³ at Rubidoux. The chemical characterizations of the PM[sub2.5] and PM[sub10] concentrations, as well as their spatial variations, were examined; the important findings are summarized in this paper, anti the temporal variations are discussed in the companion paper. [ABSTRACT FROM AUTHOR]

Although there have been several studies examining emissions of criteria pollutants from in-use alternative fuel vehicles (AFVs), little is known about emissions of hazardous air pollutants (HAPs) from these vehicles. This paper explores HAP tailpipe emissions from a variety of AFVs operating in the federal government fleet and compares these emissions to emissions from identical vehicles operating on reformulated gasoline. Emissions estimates are presented for a variety of fuel/model combinations and on four HAPs (acetaldehyde, 1,3-butadiene, benzene, and formaldehyde). The results indicate that all AFVs tested offer reduced emissions of HAPs, with the following exceptions: ethanol fueled vehicles emit more acetaldehyde than RFG vehicles, and ethanol- and methanol-fueled vehicles emit more formaldehyde than RFG vehicles. The results from this paper can lead to more accurate emissions factors for HAPs, thus improving HAP inventory and associated risk estimates for both AFVs and conventional vehicles. [ABSTRACT FROM AUTHOR]

A large body of literature published in recent years suggests increased health risk due to exposure of people to air pollution in close proximity to roadways. As a result, there is a need to more accurately represent the spatial concentration gradients near roadways to develop mitigation strategies. In this paper, we present a practical, readily adaptable methodology, using a "bottom-up" approach to develop a detailed highway vehicle emission inventory that includes emissions for individual road links. This methodology also takes advantage of geographic information system (GIS) software to improve the spatial accuracy of the activity information obtained from a Travel Demand Model. In addition, we present an air quality modeling application of this methodology in New Haven, CT. This application uses a hybrid modeling approach, in which a regional grid-based model is used to characterize average local ambient concentrations, and a Gaussian dispersion model is used to provide texture within the modeling domain because of spatial gradients associated with highway vehicle emissions and other local sources. Modeling results show substantial heterogeneity of pollutant concentrations within the modeling domain and strong spatial gradients associated with roadways, particularly for pollutants dominated by direct emission. [ABSTRACT FROM AUTHOR]

The shipping industry has been an unrecognized source of criteria pollutants: nitrogen oxides (NOx), volatile organic compounds, coarse particulate matter (PM10), fine particulate matter (PM2.5), sulfur dioxide (SO2), and carbon monoxide (CO). Liquefied natural gas (LNG) has traditionally been transported via steam turbine (ST) ships. Recently, LNG shippers have begun using dual-fuel diesel engines (DFDEs) to propel and offload their cargoes. Both the conventional ST boilers and DFDE are capable of burning a range of fuels, from heavy fuel oil to boil-off-gas (BOG) from the LNG load. In this paper a method for estimating the emissions from ST boilers and DFDEs during LNG offloading operations at berth is presented, along with typical emissions from LNG ships during offloading operations under different scenarios ranging from worstcase fuel oil combustion to the use of shore power. The impact on air quality in nonattainment areas where LNG ships call is discussed. Current and future air pollution control regulations for ocean-going vessels (OGVs) such as LNG ships are also discussed. The objective of this study was to estimate and compare emissions of criteria pollutants from conventional ST and DFDE ships using different fuels. The results of this study suggest that newer DFDE ships have lower SO2 and PM2.5/PM10 emissions, conventional ST ships have lower NOx, volatile organic compound, and CO emissions; and DFDE ships utilizing shore power at berth produce no localized emissions because they draw their required power from the local electric grid. [ABSTRACT FROM AUTHOR]

This paper summarizes information on the spatial and temporal variability of selected air toxics pollutants collected on a national basis primarily for a period encompassing 1990-2003. Spatial information on pollutant concentrations is characterized in terms of within-city and between-city variability. Temporal information is summarized as diurnal and seasonal variability and in multiyear trends. The information on variability is presented in the framework of a larger need for systematic documentation of information on air toxics pollutants to assess progress in air pollution control programs. [ABSTRACT FROM AUTHOR]

This paper presents a technique to study air pollution by combining high spatial resolution data obtained by a mobile platform and those measured by conventional stationary stations. Conventional stations provide time-series point data but cannot yield information that is distant from the sites. This can be complemented or supplemented by mobile measurements in the vicinity of the conventional sites. Together, the combined dataset yields a clearer and more precise picture of the dispersion and the transformation of pollutants in the atmosphere in a fixed time frame. Several experiments were conducted in the years 2002-2003 to track the impact of power plant plumes on ground receptors in the immediate vicinity (within a radius of 30 km) of the plants, using a combined mobile and stationary dataset. The mobile data allowed the identification of emissions from coal-fired and gas- fired power plants. Coal-fired power plants were the major source of sulfur dioxide (SO2), whereas nitrogen oxides (NOx) emitted from the gas-fired power plant played an important role in the formation of ozone (O3) at ground level. The mobile data showed that two particle size distribution regimes were detected: one had a dominant accumulation mode at 0.40-0.65 µm and the other at 0.65-1 µm. The existence of particles characterized by their mode at 0.65-1 µm and formed by in-cloud processes suggests that vehicular emissions were not the important source. Other local sources, such as power plants (elevated emission), were the likely sources, because Hong Kong does not have much manufacturing industry. [ABSTRACT FROM AUTHOR]

There are 188 air toxics listed as hazardous air pollutants (HAPs) in the Clean Air Act (CAA), based on their potential to adversely impact public health. This paper presents several analyses performed to screen potential candidates for addition to the HAPs list. We analyzed 1086 HAPs and potential HAPs, including chemicals regulated by the state of California or with emissions reported to the Toxics Release Inventory (TRI). HAPs and potential HAPs were ranked by their emissions to air, and by toxicity-weighted (tox-wtd) emissions for cancer and noncancer, using emissions information from the TRI and toxicity information from state and federal agencies. Separate consideration was given for persistent, bioaccumulative toxins (PBTs), reproductive or developmental toxins, and chemicals under evaluation for regulation as toxic air contaminants in California. Forty-four pollutants were identified as candidate HAPs based on three ranking analyses and whether they were a PBT or a reproductive or developmental toxin. Of these, nine qualified in two or three different rankings (ammonia [NH[sub3]], copper [Cu], Cu compounds, nitric acid [HNO[sub3]], N-methyl-2-pyrrolidone, sulfuric acid [H[sub2]SO[sub4]], vanadium [V] compounds, zinc [Zn], and Zn compounds). This analysis suggests further evaluation of several pollutants for possible addition to the CAA list of HAPs. [ABSTRACT FROM AUTHOR]

Particulate matter (PM) is a ubiquitous air pollutant that has been receiving increasing attention in recent years due in part to the association between PM and a number of adverse health outcomes, including mortality and increases in emergency room visits and respiratory symptoms, as well as exacerbation of asthma and decrements in lung function. As a result, the ability to accurately sample ambient PM has become important, both to researchers and to regulatory agencies. The federal reference method for the determination of fine PM as PM[sub2.5] in the atmosphere recommends that particle-sampling filters be conditioned and weighed in an environment with constant temperature and relative humidity (RH). It is also recommended that vibration, electrostatic charges, and contamination of the filters from laboratory air be minimized to reduce variability in filter weight measurements. These controls have typically been maintained in small, environmentally controlled "cleanrooms." As an alternative to constructing an elaborate cleanroom, we have designed, and presented in this paper, an inexpensive weighing chamber to maintain the necessary level of humidity control. [ABSTRACT FROM AUTHOR]

To facilitate routine health risk assessments, we develop the concept of an inhalation transfer factor (ITF). The ITF is defined as the pollutant mass inhaled by an exposed individual per unit pollutant mass emitted from an air pollution source. A cumulative population inhalation transfer factor (PITF) is also defined to describe the total fraction of an emitted pollutant inhaled by all members of the exposed population. In this paper, ITFs and PITFs are calculated for outdoor releases from area, point, and line sources, indoor releases in single zone and multizone indoor environments, and releases within motor vehicles. Typical PITFs for an urban area from emissions outdoors are ∼ 10[sup-6]-10[sup-3]. PITFs associated with emissions in buildings or in moving vehicles are typically much higher, ∼ 10[sup-3]-10[sup-1]. [ABSTRACT FROM AUTHOR]

A prototype instrument, designed for continuous monitoring of hazardous air pollutant metal emissions in the stack gases of waste incinerators and industrial furnaces, has undergone a performance evaluation that included a relative accuracy test audit. The test results confirmed the instrument's ability to accurately measure stack gas metal concentrations and thus validate the applicability of the candidate technique for compliance assurance monitoring for the specific source involved. The analytical accuracy of this system, documented during the recent test exercise, represents a significant improvement in performance relative to that previously achieved, and can be attributed with certainty to the recent implementation of a shrouded nozzle sampling system. By reducing deposition losses of particulate matter in the extracted stack gas stream to acceptable levels, presentation of a more representative sample stream to the elemental analyzer has been accomplished. The present paper discusses the design and operation of the multimetals continuous emissions monitor (MMCEM), the shrouded nozzle sampling system, and the results of recent performance testing. [ABSTRACT FROM AUTHOR]

In air pollution epidemiology, error in measurements of correlated pollutants has been advanced as a reason to distrust regressions that find statistically significant weak associations. Much of the related debate in the literature and elswhere has been qualitative. To promote quantitative evaluation of such errors, this paper develops an air pollution time-series model based on correlations among unit-normal variables. Assuming there are no other sources of bias present, the model shows the expected amount of relative bias in the regression coefficients of a bivariate regression of coarse and fine particulate matter measurements on daily mortality. The model only requires information on instrumental error and spatial variability, along with the observed regression coefficients and information on the true fine-course correlation. Analytical results show that if one pollutant is truly more harmful than the other, then it must be measured more precisely than the other in order not to bias the ratio of the fine and course regression coefficients. Utilizing published data, a case study of the Harvard Six-Cities study illustrates use of the model and emphasizes the need for data on spatial variability across the study area. Current epidemiology time-series regressions can use this model to address the general concern of correlated pollutants with differing measurement errors. [ABSTRACT FROM AUTHOR]

An air pollution index is a quantitative tool through which air pollution data can be reported uniformly. There have been efforts to describe overall air pollution by an aggregation of pollutant subindices. When ambiguous, these aggregations raise unnecessary alarm by declaring a less polluted air to be highly polluted. Similarly, when eclipsed, a false sense of security is provided by indicating highly polluted air as less polluted. Linear sum and root sum square forms in vogue suffer from ambiguity. Whereas the maximum operator aggregation does not consider change in the remaining pollutants, it is not a good tool for management purposes. In this paper, an ambiguity and eclipsicity-free function has been presented for aggregation of air pollution subindices. For computer adaptation of the aggregation process, the subindices have been expressed as full range functions of the pollutant concentrations. [ABSTRACT FROM AUTHOR]