Suchergebnisse

This paper examines the contribution of primary and secondary NO2 production in NOx concentrations and offers a comprehensive analysis of the long-term trends of NOx, NO2 and O-3 concentrations, as well as of the NO2/NOx ratio, in the Athens urban conurbation. Long-term pollutant concentration time series show that NO2 concentrations in Athens have decreased since 1987 but at a slower rate than those of NOx, resulting to an increasing NO2/NOx concentration ratio. However, this increasing trend is much smaller than those observed in urban areas of other European countries. The possible causes of this trend are examined and especially the interaction with ozone and the amount of direct NO2 traffic emissions. The results indicate that the increasing NO2/NOx ratio in the Athens area is mainly attributable to an increased secondary formation of NO2 through photochemical reactions in the atmosphere. More specifically, two different empirical methodologies were applied to examine the primary NO2 concentration fraction in Athens, using ambient monitoring data from a kerbside station. Both methods indicate that the primary NO2 concentration share has not altered significantly between 1998 and 2006. This is mainly attributed to the fact that in the Athens area diesel passenger cars are not allowed and after-treatment technologies such as particle filters and oxidation catalysts are not yet applied in Greece. A probable future penetration of diesel passenger cars in Athens should be combined with inventories of primary NO2 emissions and with the development of appropriate policies to reduce ambient NO2 concentrations below the EU limit values. (C) 2010 Elsevier Ltd. All rights reserved.

Several characteristics of the annual PM10 concentrations in the Athens conurbation, together with the expected health implications, are investigated using data from the Athens network of monitoring stations. Annual PM10 concentrations show a decreasing trend; however, concentration levels are still high, exceeding the current EU air quality standard at four monitoring stations and the Air Quality Guideline (AQG) suggested by WHO at all eight stations. PM10 concentrations correlate well with those of NOx and NO2, while the results suggest that approximately 54% of the PM10 fraction is attributable to road traffic. An analysis of the health implications of the observed PM10 levels, based on a dose-response relationship, is coupled with available health-related data from the Athens area. This analysis suggests that if PM10 concentrations were reduced to the levels of the AQGs, then a significant decrease in respiratory and cardiovascular hospital admissions and mortality would be observed. Copyright © 2010 Inderscience Enterprises Ltd.

Recent risk assessment studies have shown that high outdoor NO, levels observed in residential areas contribute to increased respiratory and cardiovascular diseases and mortality. Detailed information on present NO2 levels as well as predictions of NO2 concentrations corresponding to reduced NOx levels in urban areas are very useful to decision and policy makers in order to protect the public health. In the present paper, monitoring stations of the Athens network are initially classified into two main groups, traffic affected and urban background, using effectively a criterion based on the ratio of annual mean NO:NO2 concentrations. Two empirical methodologies are then considered and compared for assessing the effect of different NOx levels on the attainment of the annual NO2 air quality standard at urban-background locations in the Athens area. An interesting finding is that these two methodologies, one more general and one both year and site dependent, give similar results for the specific study area and can be applied alternatively based on the length of available concentration time series. The results show that in order to meet the EU annual mean NO2 objective at all the urban-background locations of the Athens area, annual NOx concentrations should be reduced to approximately 60 mu g m(-3), requiring NOx emission reductions of up to 30%. An analysis of the health implications of the currently observed NO, levels is conducted, based on a dose-response relationship, and is coupled with available health-related data for the Athens area. This analysis suggests that if NO2 concentrations were reduced to the levels of the annual EU air quality standard, then a decrease of hospital admissions of up to 2.6% would be observed, depending on the levels of NO2 measured at different monitoring sites of the Athens conurbation. (C) 2007 Elsevier Ltd. All rights reserved.

It is very useful for the authorities and the people to have daily easy understandable information about the levels of air pollution and the proper measures to be taken for the protection of human health. In this paper we develop an aggregate Air Quality Index (AQI) based on the combined effects of five criteria pollutants (CO, SO2, NO2, O-3 and PM10) taking into account the European standards. We evaluate it for each monitoring station and for the whole area of Athens, Greece, an area with serious air pollution problems. A comparison was made with a modified version of Environmental Protection Agency/USA (USEPA) maximum value AQI model adjusted for European conditions. Hourly data of air pollutants from 4 monitoring stations, available during 1983-1999, were analysed for the development of the proposed index. The analysis reveals the Athenian population exposure reaches high levels and during last years a gradual increase of days with unhealthy conditions was detected. The proposed aggregate model estimates more effectively the exposure of citizens comparing with the modified USEPA maximum value model, because counts the impact of all the pollutants measured. Towards the informing and protection of the citizens in an urban agglomeration this model advantages as a political and administrative tool for the design of abatement strategies and effective measures of intervention. (c) 2007 Elsevier Ltd. All rights reserved.

Goal, Scope and Background. This paper describes a statistical modelling approach, suggested as a policy tool in the Athens area for the assessment of the emissions reduction level required to meet the air quality standards for two criteria air pollutants, namely CO and NO2. Methods. More than ten years of hourly CO and NOx-NO2 concentration data measured by the monitoring network of the Hellenic Ministry for the Environment, Physical Planning and Public Works were analyzed and the original dataset has been reduced using a data evaluation procedure. Results and Discussion. Seasonal pollutant concentration trends suggested that the reduction of CO and NOx concentrations observed in the beginning of the '90s is almost entirely attributed to the increase of the catalyst-equipped cars during this period. The numerical parameters of an empirical model relating EU standard exceedances with mean annual concentrations were defined and the model was validated using datasets from years that were not used for the estimation of these parameters. This model was used in conjunction with a roll-back equation as a policy tool for the assessment of the effect of different CO and NOx emissions reduction scenarios on air quality standard compliance for CO and NO2. Results predicted with this empirical modelling approach were assessed with monitored data averaged over a 3-year period, giving satisfactory results. Conclusion. A methodology suggested for assessing the effects of different emissions reduction scenarios on air quality standard attainment was successfully applied for CO and NO2 in the Athens area. Recommendation and Perspective. The proposed methodology can provide a useful tool for the evaluation of policies already in progress as well as the development of future policies for emissions reduction in urban areas with similar characteristics, aiming at air quality standard compliance on a timely manner. Such a methodology could be applied in other urban areas of Greece characterized by dense traffic, therefore assisting the development of national policies in relation to air pollutants for which standard exceedances occur. © 2007 ecomed publishers (Verlagsgruppe Hüthig Jehle Rehm GmbH).

This study presents the results of a yearlong PM10 measurement campaign, conducted at four sampling sites, within the Greater Athens Area, between June 2001 and May 2002. Daily average PM10 concentrations were determined using reference samplers installed in two urban locations (Maroussi and Aristotelous), a mixed urban-industrial location (Elefsina) and a background location (Thrakomacedones). The 24-h and annual PM10 average concentrations were calculated and compared to the corresponding air quality standards, promulgated by the European Union, revealing severe exceedances of the limit values. The mean concentrations for the sampling periods were 73.8, 83.2, 32.9 and 54.9 mug/m(3) for Maroussi (MAR), Aristotelous (ARI), Thrakomacedones (THR) and Elefsina (ELE), respectively. The spatial variation of PM10, was investigated resulting at a coefficient of variation of 0.36 within the study area and correlation coefficients ranging from 0.57 to 0.84. In addition, strong associations between PM10 and other primary gaseous pollutants were found. Regression analysis of PM10 against NOx (used as an indicator for road traffic emissions) revealed significant vehicular contributions to the measured PM10 concentrations. Higher PM10 levels were recorded during prevailing winds of the S-SW sectors, while lower levels were observed during strong northerly flows. The overall results allowed a first assessment of the severity of PM10 air pollution in the Athens basin, and of the potential sources responsible for it. The control of traffic-related particle emissions appears to be a principal objective, for the confrontation of the PM10 pollution problem affecting the area.

During the period of 1 June 1999 through 31 May 2000, PM2.5 and PM10 concentrations were measured in downtown Athens, Greece. The monitoring site was located 6.7 m above ground near a highly trafficked and congested road. Daily PM10 and PM2.5 samples were collected using semi-automatic low-volume samplers. The average 24-h PM10 concentration during the sampling period was 75.5 mug/m(3). Daily PM10 concentrations exceeded the European Union limit (for the year 2000) for approximately 42% of the sampling days. The average PM2.5 measured concentration was 40.2 mug/m(3), which is considerably higher than the United States National Ambient Air Quality PM2.5 annual standard, 15 mug/m(3). The mean coarse particle concentration, PM10 minus PM2.5, was 35.3 mug/m(3) representing about 50% of the average PM10. PM2.5 and PM10 concentrations were highly correlated with carbon monoxide, black carbon and nitrogen oxides and inversely correlated with local wind speed. Regression models using continuous and categorical variables were developed to investigate the complex relationships between meteorological and time period parameters and particle concentrations. The results of this analysis underlined the importance of local emission sources, mostly from traffic, which are responsible for the high PM10 and PM2.5 concentration levels observed during this one year-sampling period. (C) 2003 Elsevier Science Ltd. All rights reserved.

This study presents results from a yearlong particulate matter measurement campaign, conducted across the Greater Athens Area, at four locations, between 1st June 2001 and 31st May 2002. The collected PM10 24-h samples were analyzed for nine toxic metals and metalloids (Pb, As, Cd, Ni, Cr, Mn, V, CLI, Hg). Concerning the five elements regulated by the European Union, annual average concentrations of Ph were found below the limit values at all sites, Cd and Ni concentrations were lower than the prospective assessment thresholds at all sites, concentrations of As exceeded the assessment threshold at two sites, while concentrations of Hg were found below detection limits in all samples. Concentration levels of Mn and V were in compliance with the values proposed by the World Health Organization. The seasonal and spatial variability of metal concentrations was examined and site-specific correlation analysis was conducted for the identification of metals with similar origin. The association between trace metals and NO, concentrations was explored to account for the impact of automotive sources, at two traffic-impacted sites. Cu was the metal most closely linked with the road transport sector. The relation of concentration levels with the prevalence of winds from different sectors was studied in an effort to investigate the transport of metal particles from various zones of the city. Finally, factor analysis was carried out to extract the main components responsible for the variance of the dataset and to attribute them to specific source categories, with vehicle-related sources being important in all cases. (c) 2005 Elsevier Ltd. All rights reserved.

In the present paper, 1-year PM10 and PM 2.5 data from roadside and urban background monitoring stations in Athens (Greece), Madrid (Spain) and London (UK) are analysed in relation to other air pollutants (NO,NO2,NOx,CO,O3 and SO2)and several meteorological parameters (wind velocity, temperature, relative humidity, precipitation, solar radiation and atmospheric pressure), in order to investigate the sources and factors affecting particulate pollution in large European cities. Principal component and regression analyses are therefore used to quantify the contribution of both combustion and non-combustion sources to the PM10 and PM 2.5 levels observed. The analysis reveals that the EU legislated PM 10 and PM2.5 limit values are frequently breached, forming a potential public health hazard in the areas studied. The seasonal variability patterns of particulates varies among cities and sites, with Athens and Madrid presenting higher PM10 concentrations during the warm period and suggesting the larger relative contribution of secondary and natural particles during hot and dry days. It is estimated that the contribution of non-combustion sources varies substantially among cities, sites and seasons and ranges between 38-67% and 40-62% in London, 26-50% and 20-62% in Athens, and 31-58% and 33-68% in Madrid, for both PM10 and PM 2.5. Higher contributions from non-combustion sources are found at urban background sites in all three cities, whereas in the traffic sites the seasonal differences are smaller. In addition, the non-combustion fraction of both particle metrics is higher during the warm season at all sites. On the whole, the analysis provides evidence of the substantial impact of non-combustion sources on local air quality in all three cities. While vehicular exhaust emissions carry a large part of the risk posed on human health by particle exposure, it is most likely that mitigation measures designed for their reduction will have a major effect only at traffic sites and additional measures will be necessary for ...