Showing papers on "Air pollutant concentrations published in 2000"

Environmental air pollution.

Abstract: The effects of air pollution on health have been recognized for many hundreds of years. In London, during December 1952, a particularly bad smog, which involved extreme elevations of both SO 2 and black smoke, was associated with more than 1,000 extra deaths during a 5-d period (1). The majority of the pollution responsible for smogs is derived from the domestic and industrial burning of fossil fuels. The introduction of legislation to reduce the burning of fossil fuels in Britain and elsewhere has meant that the make-up of environmental air pollution has changed considerably. However, the decline in fossil fuel-associated pollutants has been replaced by a steady increase in traffic-associated pollutants such as finer, respirable particulates, oxides of nitrogen (NOx), ozone (O 3 ), and volatile organic compounds (VOCs).

Models for air quality management and assessment

Abstract: Models which could be useful for estimating air pollutant concentrations as a function of the emission distribution and the attendant meteorological conditions have been investigated. The integration of this model into an emission control scheme for the control of the pollution sources may represent a very useful approach to air quality management and assessment. A novel black box approach for air pollution modeling has been proposed. The main target of this approach is the prediction, on the basis of meteorological forecasts, of the air pollution concentration as a function of the expected causes.

Health Risks from Indoor Air Pollutants: Public Alarm and Toxicological Reality

Abstract: The air, particularly the indoor air, contains a considerable burden of unwanted pollution. Overall there may be thousands of pollutants. They are brought in with the outside air or are generated from

Monitoring and Assessment of Exhaust Emission in Bangkok Street Air

Abstract: Measurement of the exhaust emission from gasoline-powered motor vehicles in Bangkok were performed on chassis dynamometer. A fleet of 10 vehicles of different model, years and manufacturers were selected to measure the air pollutants in the exhaust effluent. The study revealed that the carbon monoxide and hydrocarbon emissions averaged 32.3–64.2 and 1.82–2.98 g km−1, respectively, for 1990–1992 cars and decreased to 17.8–40.71 and 0.75–1.88 g km−1, respectively, for 1994–1995 cars. A monitoring program for air pollutant concentrations in ambient air was also conducted to evaluate the air pollution problems in Bangkok arising from vehicle exhaust emission. Four air sampling stations were strategically established to cover the Bangkok Metropolitan Region (BMR). Composite air samples in this study area were collected during the day/night times and weekday/weekend. The average concentrations of suspended particulate matter, carbon monoxide, and nitrogen dioxide in Bangkok street air were found to be 0.65 mg/m3 (24 hr ave.), 19.02 mg/m3 (8 hr ave.) and 0.021 mg/m3 (1 hr ave.), respectively. The average concentrations of benzene and toluene in the ambient air of the study area were found to be 15.07–50.20 and 25.76–130.95 μg/mf3, respectively, for 8 hr average. These results indicated that there was a significant increase in air pollutant emissions with increasing car mileage and model year. Subsequent analysis of data showed that there were only 20% of the test vehicles complied to approved emission standard. The finding also revealed that there was a correlation between the average air pollutant concentrations with average traffic speed in each traffic zone of the Bangkok Metropolitan Region (BMR).

Relationships between environmental factors and lung function of asthmatic subjects in south east Queensland, Australia.

Abstract: Few panel studies have investigated the relationships between air pollutants and air spora and lung function change in asthmatic subjects. This article examines the association of outdoor air pollutant concentrations and air spora with the decrease in lung function (measured by morning peak expiratory flow) of two groups of asthmatic subjects in the subtropical environment of South East Queensland, Australia. Lung function responses were stratified by age, allergy status, and location, and seasonal effects were examined. Allergy status and age were found to be important, with air pollutants such as ozone and particles associated with decreases in lung function in allergic individuals older than 15 years. Fungal spore counts were strongly associated with a decrease in lung function in allergic adults, especially in those over 54 years, only in seasons when these air spora peak. Analysis for the entire study period indicates that the effect of ozone on peak expiratory flow in the allergic group can sometimes be confounded by air spora effects, indicating that in a subtropical climate the impact of ozone on asthma severity can be accurately estimated only when the confounding effects of air spora are included.

Application of a parallel photochemical air quality model to the Campania region (southern Italy)

Abstract: During most of the year, the concentrations of both primary and secondary air pollutants over the Campania region (southern Italy) do not comply with the Italian air quality standards. To gain insight into the chemical and meteorological processes that lead to high air pollutant concentrations over this area, the parallel package PNAM (Parallel Naples Airshed Model) has been developed, for the numerical simulation of photosmog episodes on urban and regional scale domains. PNAM has been applied to a photosmog episode which occurred on 26 July 1995. On this day, due to the stagnant conditions and the intensive solar radiation, a high ozone concentration was reported for the Naples basin. The performance of PNAM has been assessed by comparing measured air quality data with simulated data for O3, NO, NO2 and CO. PNAM was able to reproduce temporal and spatial characteristics of measured air quality data, although some discrepancies were evident, probably mainly due to the emission inventory, which was based only on total annual emissions.

Evaluation of a traffic demand management strategy to improve air quality in urban areas

Abstract: Congestion not only has an effect on the network efficiency, but can be linked closely to roadside and background air pollutant concentrations. However, there have been very few studies that have assessed and quantified the impact of different traffic demand management strategies (TDMS) to reduce pollutant concentrations in air quality management areas. This study, funded by the DETR designed, implemented and evaluated a gating strategy upstream of a series of congested junctions which are within a street canyon, in the city of Leicester, UK. The evaluation of the TDMS involved a two month monitoring campaign, covering the period before and after implementation. Traffic flow characteristics, carbon monoxide levels, background levels and meteorological conditions were simultaneously recorded. This study has brought together the achievements of several years of research carried out by the iC research team developing measures and methods for evaluation, congestion identification and linking air pollutant levels with traffic related emission sources.

Air Pollution Control Methods

Abstract: Air pollution may be rendered less harmful by reducing the concentration of contaminants, the exposure time, or both. Selection of pollution control methods is generally based on the need to control ambient air quality in order to achieve compliance with standards for criteria pollutants, the need to reduce emission to the atmosphere of a hazardous air pollutant, or in the case of nonregulated contaminants, to protect human health and vegetation. There are three elements to a pollution problem: a source, a receptor affected by the pollutants, and the transport of pollutants from source to receptor. Modification or elimination of any one of these elements can change the nature of a pollution problem. The classes of pollutants include gases and particulates; odors are often discussed separately. To achieve air pollution control, reliable measurements are needed to quantify both the pollutant concentration and the contribution of individual sources. These data are necessary for designing control equipment, for monitoring emissions, and for maintaining acceptable ambient air quality. Two categories of measurement techniques are ambient and source measurement. Ambient sampling may help to establish and operate a pollution alert network, monitor the effect of an emission source, predict the effect of a proposed installation, locate the source of an undesirable pollutant, or obtain permanent sampling records for legal action or for modifying regulations. Source sampling problems are distinct from those of ambient sampling. Source gas may have a high temperature or contain high concentrations of water vapor or entrained mist, dust, or other interfering substances. Typical objectives of source sampling are demonstrating compliance with regulations, obtaining emission data, and determining the need for maintenance of process or control equipment. The Clean Air Act in 1990 has three areas of emphasis: acid rain reduction in the northeastern United States; severe limitation on atmospheric emissions of 189 chemicals on the hazardous or Toxic Substance list; and tightened regulations on vehicular exhaust (ozone compliance and smog reduction). Five methods are available for controlling gaseous emissions: absorption, adsorption, condensation, chemical reaction, and incineration. Atmospheric dispersion from a tall stack is now less viable. Adsorption is desirable for contaminant removal down to extremely low levels. Condensation is best for substances having rather high vapor pressures. Incineration is used to remove organic pollutants and small quantities of H2S, CO, and NH3. Specific problem gases such as sulfur and nitrogen oxides require combinations of methods. Major sources of sulfur dioxide are the combustion of sulfur-containing fossil fuels, sulfur recovery from petroleum processing, and pulp and paper manufacture. Combustion emissions are controlled by substituting a low sulfur fuel source, by fuel desulfurization and refining, and by sulfur removal either in the combustion process or from the flue gas. Major sources of nitrogen oxide emission are nitrogen fixation during high temperature combustion, nitric acid manufacture and concentration, and vehicular emissions. NO formation in combustion may be reduced by maintaining low excess air, employing two-stage combustion, flue gas recirculation, and burner placement. The removal of particles (liquids, solids, or mixtures) from a gas stream requires deposition and attachment to a surface. Devices for particle collection by filtration can be divided into three categories: cloth filtration, paper and mat filters, and in-depth aggregate bed filtration. Scrubbers can be highly effective for both particulate collection and gas absorption. Scrubbers make use of a combination of particulate collection mechanisms. Wet-scrubber collection efficiency may be unexpectedly enhanced by particle growth. Vapor condensation produced by cooling, can lead to particle growth or agglomeration. Keywords: Air pollution; Measurements; Control regulations; Control cost; Control equipment; Gaseous emissions; Particulate emissions; Odor; Sampling; Control

The impact of an airport on regional air quality at Munich, Germany

Abstract: In May 1992, the new airport in Munich, Germany, became fully operational. In 1991, two research programmes within the Bavarian Climate Research Programme (BayFORKLIM) in Germany/Bavaria were established to measure, calculate and model the assumed change of the air quality in the vicinity of the new airport. By analysing the synoptic and local weather situation, measured and modelled air pollution distribution modifications in the air quality can be recognised. The results show no effect on the ozone but some effect in the NOx concentrations. The sum of NOx (NO + NO2) concentrations shifts towards lower NO and higher NO2) concentrations. The morning peak of the NO maximum occurs about one hour later than before the operation. During the weekend a significant increase of NOx is seen within a range of 6 to 7 ppbv. The modelling studies indicate that emissions from motor vehicles are the predominant source of NOx, aircraft emissions are of lesser importance.

Air Pollution and Potential Control Schemes in Lanzhou

Abstract: By using the existing data on air pollution sources and air quality monitoring,the situationof air pollution and its control in Lanzhou is analyzed.It is shown that coal stands 71% of the total energy resources.The annual discharge of SO 2 and soot is respectively 59\^6kt and 65\^4kt.Moreover,tail gas has become one of the main air pollution sources.According to the data analysis during the heating period,the daily mean value of SO 2 concentration in the city exceeds the second grade of the Ambient Air Quality Standard of China,and that of TSP concentration also stays high over the Standard throughout the year.Therefore,centralized heating system,gas and briquette schemes,and tail gas control are taken as the major feasible measures in planning the urban air pollution control projects.At the same time,planting trees and solar energy should also be taken into consideration for the air pollution control schemes.

A Sensitivity Study of Parameters in the Nazaroff-Cass IAQ Model with Respect to Indoor Concentrations of O3, NO, NO2

Abstract: The indoor O3, NO, NO2 concentrations and their corresponding indoor/outdoor (I/O) concentration ratios are predicted in this paper for some representative buildings, using the Nazaroff-Cass indoor air quality model. This paper presents and systemizes the relationship between indoor air pollutant concentrations and the building's design, use and operation. The building parameters which are determined to be main factors affecting the air pollutant concentrations are: the physical dimensions of the building and the materials of construction, the building's air exchange rate with outdoors and the indoor air pollutant sources. Changes of ultraviolet photon fluxes, of temperature and of relative humidity indoors, have little effect on indoor O3, NO and NO2 concentrations, for air exchange rates above 0.5 ach. Special attention must be given when a building has a very low air exchange rate, under which conditions the effect of a small change in any of the factors determining the indoor air quality of the buildi...

Air pollution and the aggravation of the symptoms of COPD in children

Abstract: Studies conducted in Zagreb reported a short-term relation between air pollutant concentrations and emergency hospital visits due to the aggravation of symptoms of the chronic obstructive pulmonary disease (COPD). Air pollution in Zagreb is generally below the limit, and usually within the values recommended by the World Health Organization. Daily variations in the number of emergency room visits due to COPD were modeled in relation to daily variations in air pollution for the period 1995-1997. A generalized additive model for Poisson distribution was used, controlling for possible confounders, seasonality, trend, and autoregressive patterns. The effect of NO/sub 2/ was linear and significant with relative risk associated with a 50 /spl mu/gm/sup -3/ increase in NO/sub 2/ concentrations equal 1.297 (95% confidence limits 1.026-1.639). The effect of SO/sub 2/ was also linear, but not statistically significant, and that of black smoke was significantly nonlinear and of an intriguing U shape. The COPD emergency visits increased when black smoke concentrations decreased below 36 /spl mu/gm/sup -3/ (the 75th percentile) and increased above 48 /spl mu/gm/sup -3/ (the 90th percentile). This finding is attributed to possible confounding with ozone.

Properties and Sources of Common Ambient Air Pollutants

Abstract: Air pollution has been around as long as human populations. Most likely one of the first major human causes of air pollution was fire. Along with the invention of fire, we assume, came exposure to various types of smoke. Interestingly, wood smoke is still a primary source of fine particulate matter air pollution in some areas where wood burning is used for home heat or cooking or for clearing of slash.