Showing papers on "Air pollutant concentrations published in 1998"

Air pollutant uptake by Sacramento's urban forest.

Abstract: A dry deposition model was employed to estimate air pollutant uptake by Sacramento's urban forest. Assuming 1990 air pollutant concentrations, model simulations estimated that approximately 1,457 metric tons of air pollutant are absorbed annually, at an implied value of US$28.7 million. The growing season daily uptake for ozone was approximately 2.4 metric tons per day, while particulate matter (< 10 μ diameter, PM10) uptake was slightly greater, at 2.7 metric tons per day. Daily uptake of NCX, and particulate matter represented 1 % to 2% of anthropogenic emissions for the county. Estimated growing-season annual air pollutant uptake rates averaged 10.9 kg/(ha land area per yr) for the entire study area, 13.9 kg/(ha land area per yr) for urban areas and 4.2 kg/(ha land area per yr) for rural areas. Pollutant uptake rates decreased with decreasing tree canopy cover, along an urban-to-rural gradient.

Sources and Control of Air Pollution

Abstract: sources and control of air pollution studiokdev sources and control of air pollution klmvc sources and control of volatile organic air pollutants air pollution control epa air pollution engineering welcome to caltechauthors sources and control of air pollution snowlog water pollution: sources, effects, control and management state air pollution control board regulations for the technologies for air pollution control eolss point sources of pollution: local effects and control air pollution control at construction sites air pollution control regulations vermont air pollution: causes, sources and abatement ce 476/576. air pollution control fact sheet: air pollution emission control devices for outdoor air pollution who air pollution control rules and regulations sources, types and distribution of air cffet air pollution and its sources soma medical air pollution control officer placer ridem/air resources-air pollution control regulation no. 9 clean air act epa archives tuolumne county air pollution control district air pollution control dnr general regulations for air pollution sources does my business need an air pollution control permit? air pollution control regulations vermont air pollution control technology fact sheet us epa air pollution in china: mapping of concentrations and sources solution to control air pollution expoll air pollution control us epa indian journal of air pollution control harboring pollution nrdc ridem/air resources-air pollution control regulation no. 28 chapter 5 . sources of air pollution: gasoline and diesel using bioreactors to control air pollution air pollution control in china: progress and perspectives air quality in minnesota * minnesota pollution control taking control of air pollution in mexico city idrc appendix a controlling sources of toxic air pollutants mobile source air pollution control program archives air pollution and control facsys regulations for the control and abatement of air pollution air pollution uc berkeley college of natural resources air pollution control rules michigan air pollution control district imperial county website chapter 3 source control of pollution air pollution in china washington state university pollution control minnesota determining sources of environmental pollution

Application of health information to hazardous air pollutants modeled in EPA's Cumulative Exposure Project.

Abstract: Relatively little is known about the spectrum of health effects, and the scope and level of ambient air concentrations of those pollutants regulated under the Clean Air Act as "hazardous air pollutants". The U.S. Environmental Protection Agency's (USEPA) Cumulative Exposure Project uses currently available emissions inventories, from a variety of source types, and an atmospheric dispersion model to provide estimates of ambient concentrations for 148 hazardous air pollutants (HAPs) in over 60,000 census tracts for the year 1990. This paper uses currently available hazard information for those pollutants and provides a database of potential regulatory threshold concentrations of concern, or "benchmark concentrations," and a methodology for prioritizing and characterizing the quality of the data. In order to demonstrate application of the database and prioritization scheme to outputs from the Cumulative Exposure Project, comparisons were made with the maximum modeled concentration of each individual hazardous air pollutant across the census tracts. Of the 197 benchmark concentrations for cancer and non-cancer (long- and short-term exposures) effects compiled for the study, approximately one half were exceeded with a predominance of exceedance of cancer benchmarks. While the number of benchmark concentrations available to fully characterize potential health effects of these pollutants was limited (approximately 80 percent of HAPs identified as cancer concerns had benchmark concentrations for cancer and 50 percent of all HAPs had non-cancer benchmark concentrations) and there was greater uncertainty in derivation of maximum modeled air concentrations than other levels, the comparison between the two was a useful approach for providing an indication of public health concern from hazardous air pollutants.

Czech Air Quality Monitoring and Receptor Modeling Study

Abstract: An ongoing air quality monitoring program in the Czech Republic has provided nearly continuous data for the concentrations of aerosol and gas-phase pollutants since its inception in February 1992. In addition to PM-2.5 concentrations, the concentrations of sulfate, organic carbon, elemental carbon, trace elements (Al−Pb), and polynuclear aromatic hydrocarbons (PAHs) were also measured. Fine particulate matter (PM-2.5) was composed mainly of organic carbon and sulfate with smaller amounts of trace metals. Coarse particle mass concentrations were typi cally between 10 and 30% of PM-2.5 concentrations. The chemical composition of emissions from power plants, residential space heating, local factories, and motor vehicles was also characterized. The ambient monitoring and source characterization data were then used in receptor modeling calculations, the results of which indicate that residential space heating and power plant emissions ac counted for most of fine particle mass concentrations observed during win...

Health impacts of biomass air pollution

Abstract: In 1997, uncontrolled forest fires burning in Indonesia resulted in a regional air pollution episode of smoke which impacted several Southeast Asian nations. Beginning in late July 1997, elevated levels of particulate matter air pollution were observed for a period of approximately 2 months in many areas, with a severe episode occurring during most of the month of September. During this episode, particle levels in some areas were up to 15 times higher than normal levels. Exposures to “haze”-type air pollution can be substantial and are of public health concern due to the large numbers of individuals who may be exposed.

Assessment of a bayesian multivariate interpolation approach for health impact studies

Abstract: Health impact studies of air pollution often require estimates of pollutant concentrations at locations where monitoring data are not available, using the concentrations observed at other monitoring stations and possibly at different time periods. Recently, a Bayesian approach for such a temporal and spatial interpolation problem has been proposed by Le. Sun and Zidek (1997). One special feature of the method is that it does not require all sites to monitor the same set of pollutants. This feature is particularly relevant in environmental health studies where pollution data are often pooled together from several monitoring networks which may or may not monitor the same set of pollutants. The methodology is applied to the data in the Province of Ontario, where monthly average concentrations for summer months ofnitrogen dioxide (NO 2 in μg/m 3 ), ozone (O 3 in ppb), sulphur dioxide (SO in μg/m 3 ) and sulfate ion (SO 4 in μg/m 3 ) are available for the period from January I of 1983 to December 31 of 1988 at 31 ambient monitoring sites. Detailed descriptions of spatial interpolation for air pollutant concentrations at 37 approximate centroids of Public Health Units in Ontario using all available data are presented. The methodology is empirically assessed by a cross-validation study where each of the 31 sites is successively removed and the remaining sites are used to predict its concentration levels. The methodology seems to perform well.

Particulate Air Pollution

Abstract: The attention of the whole world was drawn to air pollution by the London fog of 1952. I was in that fog, although somewhat upriver at Oxford. To the best of my knowledge, anyone who has looked at the data from the official government report [1] shown here as Figure 1, agrees that about 4,500 people died within 2 weeks because of the air pollution.

Inventory of emissions from major air pollutant categories in Turkey

Abstract: In this study, an inventory of air pollutant emission estimates from major air polluting sources in Turkey for period between 1985 and 2005 with 5-year intervals were estimated. Inventory covers anthropogenic sources of five major air pollutants of particulate matter, sulfur dioxide, carbon monoxide, nitrogen oxides and non-methane volatile organic compounds. Their break-down with respect to main activity sectors were shown and their distribution by the largest industrial source categories were worked out as annual estimates. This inventory and its analysis point to serious environmental implications of air pollutants and a need to develop a policy plan for reducing these emissions.

The influence of vehicle emission characteristics and meteorological conditions on urban no2 concentrations

Abstract: A major fraction of nitrogen oxides released from traffic is commonly nitrogen monoxide (NO); however, the proportion of NO2 in exhaust emissions can range from less than 1% to more than 50%. The released NO is chemically transformed into the more harmful nitrogen dioxide (NO2); the reaction time-scale is typically a few minutes in urban daylight conditions. This paper presents numerical results concerning the influence of the tailpipe NO2/NOx fraction and meteorological conditions on the ambient air NO2 concentrations. We have applied the road network dispersion model CAR-FMI in the computations.

Emissions of hazardous air pollutants from aeration tanks

Abstract: Regulated under the 1990 Clean Air Act Amendments (CAAA), Publicly Owned Treatment Works (POT Ws) need to inventory and control their hazardous air pollutant (HAP) emissions, primarily from the aeration tanks. The spatial characteristics of hazardous air pollutant (HAP) emissions, primarily from the aeration tanks. The spatial characteristics of hazardous air pollutants in the form of volatile organic compounds (VOCs) from the aeration units of POTWs have been investigated by systematic monitoring and mathematical modeling. Using a verified off-gas sampling system and CC-MS analytical method, a large wastewater treatment plant has been tested to understand the air emissions from its aeration basins. Variations of VOC emissions along the length of the aeration units have been tested and modeled. Most VOCs have decreasing concentration profiles. A simple PFR model has been developed to obtain the spatial information of the VOC fate. This model can be easily used to validate model parameters and accurately simulate the process especially in the case where the aeration tanks are operated with varied airflow rates along the tank length. Using this simple model, air emissions can be accurately estimated and the simulation results are useful to support an emissions control analysis. This study also reveals thatmore » simple multiplication of measured off-gas concentration and total airflow over-estimates the overall emissions.« less

Zur statistischen Auswertung mikroskaliger Immissionsprognosen

Abstract: Microscale models are valuable tools for estimating air pollutant concentrations in urban areas. If however statistics of pollutant concentrations (including annual mean, percentile and frequency of odour nuisance) are to be derived from model calculations a large number of simulations for different meteorological situations are necessary. In this article recommendations are given explaining how to the number of simulations can be reduced without a significant loss of accuracy in the resulting air quality data. It is also shown that most applications require simulations for only four to twelve wind directions and two to three wind velocities. Following this recommendations the costs of air quality studies in urban areas can be significantly reduced.

Cold-front activities and itsinfluence on air pollution aturban districts of lanzhouin cold half year

Abstract: It has been analysed that the data of 500hPa historical synoptic maps and the data of air pollutant concentrations were monitored by automatic monitoring system in Environmental Monitoring Station of Lanzhou in the period of 1988～1991 The analysed results are as follows:under the control of two-trough and one-ridge synoptic circulation pattern the frequency of cold-front activities at Lanzhou is the highest with 548% It is higher with 355% under the control of one -ridge and one-trough synoptic circulation pattern In cold half year the activest stages of the strongest and stronger cold fronts are in March The other activer stages of cold fronts are in October The activest stages of weak cold fronts is in January Influence of cold-front passage on SO2 concentrations at Lanzhou is the most remarkable The average decreasing rate of SO2 concentration is about 30% to 50% and the maximum decreasing rate is about 70% to 80% The decreasing rate of NOx concentration is also more remarkableIn the process of cold front weather, the correlation between inversion depth and air pollutant concentration is the most remarkable The correlations between temperature, mixing depth and air pollutant concentrations respectively are reducing in proper order Influences of above mentioned three meteorological factors on the changes of air pollutant concentrations are different in the processes of the strongest, stronger and weak cold front weather

The effects of vehicular exhaust buoyancy during worst case pollution scenarios near roadways

Abstract: The California Department of Transportation (CALTRANS) has been using CALINE4, a gaussian finite line-source dispersion model, to estimate air pollutant concentrations near roadways given an estimate of traffic flow rates, vehicular emission factors, roadway geometry, and local meteorology. Modelers have typically used CALINE4 to simulate low wind near parallel thermally stable conditions to estimate a worst case pollution scenario (i.e., highest predicted pollutant concentrations) for a proposed roadway. In October 1995, the University of California, Davis (UCD), in conjunction with the CALTRANS Environmental Program, began a two-year investigation to determine if CALINE4 was adequately predicting CO concentrations during worst case meteorological conditions. Based on physical reasoning and a literature review of several highway dispersion studies conducted in the late 1970`s, it was reasoned that gaussian models may over-predict CO concentrations during worst case scenarios because these models do not adequately parameterize the increased vertical dispersion of pollutants due to vehicular emission buoyancy. To explore the role that exhaust buoyancy plays in roadway pollutant dispersion, a series of experiments were conducted on I-80 (near Sacramento) during winter pre-dawn commute hours. Results of the dispersion studies were inconclusive due to difficulty in capturing sufficiently low wind speed conditions during the sampling effort,more » however, in a compare-contrast study of field measurements versus CALINE4 predictions it was verified that CALINE4 adequately predicts both the magnitude and qualitative shape of non-worst case pollution scenarios. In addition, based on integrated mass flux from downwind CO concentration and wind profiles it was found that the use of CT-EMFAC, a regional scale emission factor model, overpredicted observed modal emissions by as much as 250 to 480%.« less

Critical health issues of criteria air pollutants

Abstract: This chapter summarizes the key health information on ubiquitous outdoor air pollutants that can cause adverse health effects at current or historical ambient levels in the United States. The Clean Air Act (CAA) of the United States requires that the US Environmental Protection Agency (EPA) identify such pollutants (called criteria pollutants) and set standards (National Ambient Air Quality Standards (NAAQS)) to protect sensitive subpopulations from the adverse effects of these compounds. The criteria pollutants are ozone, nitrogen dioxide, sulfur dioxide, particulate matter (PM), carbon monoxide (CO), and lead. The subsequent sections of this chapter focus on the individual criteria pollutants.

Air Pollution Control

Abstract: Air pollution, with its ever more apparent impacts on aquatic and terrestrial ecosystems is a typical “environmental ‘syndrome’ of the third generation”. It is not reversible with relatively simple process approaches, economically measurable costs, and within a realistic scale of time and space [5.1,5.2]. Despite clear successes in some regions, a significant worldwide reduction of air pollution will take decades. Until then the soils in many forest ecosystems will have been changed irreversibly.

Legislation on emissions of air pollutants and their monitoring

Abstract: This book is concerned with the monitoring of the emissions of air pollutants into the atmosphere from industrial processes. The reason why this topic has become such an important one in many countries is that there is an increasing weight of legislation requiring operators to provide information about gaseous and particulate substances which are released into the environment from the processes they control. The concerns which lie behind the legislation may relate to human health effects of pollutants; potential damage to other aspects of the environment (for example acid rain and ozone generation with their consequent effects, or building decay); amenity issues (for example black smoke or visibility degradation); or global issues such as climate change.