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Mining hidden knowledge from available datasets is an extremely time-consuming and demanding process, especially in our era with the vast volume of high-complexity data. Additionally, validation of results requires the adoption of appropriate multifactor criteria, exhaustive testing and advanced error measurement techniques. This paper proposes a novel Hybrid Fuzzy Semi-Supervised Forecasting Framework. It combines fuzzy logic, semi-supervised clustering and semi-supervised classification in order to model Big Data sets in a faster, simpler and more essential manner. Its advantages are clearly shown and discussed in the paper. It uses as few pre-classified data as possible while providing a simple method of safe process validation. This innovative approach is applied herein to effectively model the air quality of Athens city. More specifically, it manages to forecast extreme air pollutants’ values and to explore the parameters that affect their concentration. Also it builds a correlation between pollution and general climatic conditions. Overall, it correlates the built model with the malfunctions caused to the city life by this serious environmental problem. [ABSTRACT FROM AUTHOR]

Aviation is a basic necessity of our world, but its contribution to air pollution is considered significant. In this paper, the contribution of air traffic to air pollution levels in the area of the three larger airports of Greece is examined through the use of EDMS (Emission and Dispersion Modeling System), a regulatory model proposed by the US EPA (United States Environmental Protection Agency). To ensure a better understanding of air traffic contribution to air quality levels, the hourly aircraft movements along with the corresponding meteorological data for a whole year, 2009, were taken into account. During this year, air traffic peaked both in Greece as a total and in each of the three airports of this work. Airport emissions calculated by EDMS are found to be in good agreement with emissions monitored at Athens International Airport as well as with emission results and published data for International Zurich Airport. Concentration results have shown that PM10 and SO2 concentrations are well below the limit values, whereas NO2 concentrations exceeding limit value are expected in small areas under specific circumstances, when heavy air traffic coincides with meteorological conditions favoring air pollutant accumulation. Finally, the comparison of computational results with monitoring air quality data shows a good agreement, if other sources of air pollution are excluded. [ABSTRACT FROM AUTHOR]

The difficulty in forecasting concentration trends with a reasonable error is still an open problem. In this paper, an effort has been made to this purpose. Artificial Neural Networks are used in order to forecast the maximum daily value of the European Regional Pollution Index as well as the number of consecutive hours, during the day, with at least one of the pollutants above a threshold concentration, 24 to 72 h ahead. The prediction concerns seven different places within the Greater Athens Area, Greece. The meteorological and air pollution data used in this study have been recorded by the network of the Greek Ministry of the Environment, Physical Planning, and Public Works over a 5-year period, 2001–2005. The hourly values of air pressure and global solar irradiance for the same period have been recorded by the National Observatory of Athens. The results are in a very good agreement with the real-monitored data at a statistical significance level of p < 0.01. [ABSTRACT FROM AUTHOR]

The question to what extent primary and secondary air pollutants are relevant to atmospheric pollution and their effects on human health and the quality of the environment can be answered in a straight-forward manner: atmospheric processes, including oxidation procedures, particle formation and equilibria, determine the fate of primary emissions and, in most cases, the secondary products of these processes are the more important ones concerning their effects on human health and the quality of the environment. The formation of secondary products represents the critical property determining the establishment of certain air standards, rather than the actually emitted substance, although there are notable exceptions. In this paper, a review concerning transformation of primary pollutants as studied in the atmosphere of Athens is used to enlighten matters that may need further attention by the responsible authorities and stakeholders for the control and reduction of atmospheric pollution. [ABSTRACT FROM AUTHOR]

Within the framework of this paper an attempt is made in order to assess the relative contribution of the main diesel vehicle classes; namely, buses, taxis and heavy goods vehicles (HGVs) to the air pollution of the Thessaloniki (Greece) urban area based on an emission factors approach. Data sets refer to the situation before and after the construction of the city ring road. Findings show the significant contribution of the ring road to the urban air pollution decrease. This reduction could be mainly attributed to the observed significant traffic decrease of HGVs in the city center between 1988 and 1998. Small changes have been observed during the same period for the bus and taxi traffic in the city center. Also, the improvement of the diesel fuel quality and the temporal renewal of the diesel vehicles are considered as important factors for the observed temporal decreasing trend of the air pollutants with diesel oil origin. [ABSTRACT FROM AUTHOR]

This paper summarises the annual information on ozone monitoring stations and exceedances of ozone threshold values during 1997 transmitted by the Member States of the European Union in the framework of Council Directive 92/72/EEC on air pollution by ozone. In August 1998 information for the calendar year 1997 was received from all Member States and, on a voluntary basis, from 6 other European countries (Switzerland, Czech Republic, Latvia, Norway, Poland and Slovakia). An evaluation of the exceedances and annual statistics for 1997 clearly shows that ozone is a severe, Pan-European problem. The threshold value set for the protection of human health was exceeded substantially and in all reporting countries. The threshold value of daily average concentrations set for the protection of vegetation was exceeded substantially (by up to a factor 3), widely (in all reporting countries) and frequently (at several stations on more than 200 days). The threshold value of hourly average concentrations set for the protection of vegetation was exceeded largely and widely (reported by 10 EU Member States and in three out of the six other European countries) on a limited number of days. The threshold value for providing information to the population was exceeded in 15 countries of which 12 EU Member States during a limited number of days. Exceedance of the threshold value for warning of the population was reported from one station in Greece. [ABSTRACT FROM AUTHOR]

The present study intends to explore the relationship between tourism growth and air pollution at a regional level for five important tourism European destinations: France, Spain, Greece, Portugal, and Italy. Most of the studies found in the literature examine this relationship on a national scale and focus only on the CO2 pollutant, which is a greenhouse gas but not a critical pollutant in terms of air quality and human exposure. This research focuses on a regional basis (NUTS 2 classification) and takes into account the main critical pollutants in terms of urban air pollution (namely: NOx, PM10, and PM2.5), and considers 10 years, from 2009 until 2018. This work aims to investigate evidence of a tourism-induced Environmental Kuznets Curve (EKC) for the countries through the construction of five panels, one for each country, including different variables: the Gross Domestic Product, the energy consumption, and the number of nights spent at tourist accommodation establishments from both domestic and foreign tourists. The Levin-Lin-Chu unit root test proves the variables to be stationary, while the Pedroni cointegration test shows that they are integrated. The pooled OLS estimator is employed throughout the countries to check the relationship among the variables. Results reveal that the tourism-induced EKC hypothesis is not validated for any of the countries. The findings also show that in Portugal, Italy, and Greece, there is a negative relationship between economic growth and environmental pollution, while mixed evidence is found for France and Spain. Moreover, differences in the impacts of international and domestic tourists on air pollution are found: foreign tourists negatively impact emissions, while domestic ones increase them. This result is clear for Spain, Greece, and Italy. The Granger panel causality test is then conducted to see the causality among the variables. [ABSTRACT FROM AUTHOR]

This study explores the role of social desirability bias in the willingness to pay (WTP)–willingness to accept (WTA) disparity debate. In the context of a valuation scenario involving air quality in Athens, Greece, we examine whether the well-known WTP–WTA disparity is in place and whether social desirability could be related to this gap by introducing different magnitudes of bias on the two welfare measures. To do so, we contrast the results obtained from the contingent valuation method with those from the inferred valuation method that is believed to mitigate social desirability bias. On the policy side, the study shows that estimates of welfare loss associated with the Greek government's decision to equalize the tax on diesel fuel and heating oil, which had serious side-effects on air quality, vary greatly with respect to the value measure and method of elicitation. [ABSTRACT FROM AUTHOR]

Evidence that heat wave events are associated with poor air quality conditions and health hazards has become stronger in recent years. In this study, the impact of two heat wave episodes on human thermal discomfort and air quality is examined during summer 2007, in an industrial plain of eastern Mediterranean: the Thriassion Plain, Greece. For this purpose, two biometeorological indices-Discomfort Index (DI) and Heat Load (HL)-as well as an air quality index-Air Quality Stress Index (AQSI)-were calculated using data from seven measuring sites. A land-use map was procured in order to examine the effect of different land cover types on human thermal comfort. The results indicated high level of thermal discomfort and increased air pollution levels, while a significant correlation between the DI and the AQSI was identified. [ABSTRACT FROM AUTHOR]

An economic and quick methodology for performing a preliminary spatial assessment of a city air quality with the purpose to identify locations and zones susceptible to high pollution levels is proposed. A Patras case-study is selected, regarding the air pollutants of sulfur dioxide (SO2) and oxides of nitrogen (NOx). A total number of 451 samples of short duration, of which 225 were randomly picked in morning rush hours and 226 within evening rush hours, were collected from 50 locations of the major Patras area during a year period, when peaks of primary air pollutants usually occur. Concentration measurements at prescribed locations used to statistically calculate spatial average concentrations approximating 1-h mean values with mean probable errors less than 25.9% for SO2, NO and NOx and less than 15.5% for NO2. Then iso-concentration contour diagrams plotted indicate high pollution zones and possibly appropriate locations for continuous or random monitoring according to the European Community (EC) Directives. The 1-h mean concentrations were in good correlation to the corresponding traffic rates and useful relationships are given (0.54 ≤ r ≤ 0.63). In addition, comparisons with data available for other cities, as well as with the limit and guide values provided by the EC and the World Health Organization (WHO) were given. The present data could be useful for the design and optimization of a city network of stations for monitoring air quality, for environmental impact assessments, future reference and comparisons due to city development needs, as well as for validating dispersion models. [ABSTRACT FROM AUTHOR]

A spatially and temporally resolved atmospheric emission inventory of ozone precursor pollutants (NOx, NMVOCs and CO) was developed for the southern Balkan region in order to support air quality modelling studies focusing on Greece. The inventory is established for the reference year 2000 and it has 10 km spatial resolution. Annual anthropogenic emission data obtained from official national emission inventories and from international emission databases were spatially disaggregated and allocated to a gridded domain using the top-down methodology. Source specific temporal profiles were used in order monthly and hourly emission data to be estimated. In the study area, the highest NOx amounts are emitted by the maritime and road transport sectors. Road transport has a prominent role in anthropogenic NMVOCs emissions followed by the solvent and other product use sector. The main CO emission sources are represented by the road transport sector and the non-industrial combustion plants. In the present study, the contribution of the transport sector to the total emissions of pollutants over urban and non-urban areas of Greece is investigated. Over almost all Greek urban areas, road transport is the major NMVOCs and CO emission source. Road transport contribution to NOx emissions is greater than 50% at the large urban centres of Greece. The greater part of non-urban areas is dominated by off-road vehicle emissions. [ABSTRACT FROM AUTHOR]

The article presents a study on the sulfur dioxide (SO2) dispersion and source contribution to receptors of Downtown Patras, Greece. Air quality assessment and management are required in the development of Patras. The study aims to validate a model appropriate for predicting the dispersion of SO2, based on specific activity, weather conditions and topography. It assumes that the key contribution to air pollution in Patras is due to central heating, traffic and harbor. The US-EPA ISCLT3 integral dispersion model is used in predicting SO2 concentrations in the city. Results on the comparison of between predictions and measurements indicate that the model performance for approximating SO 2 dilutions and period pattern is satisfactory.

This article presents a methodological approach for the formulation of control strategies capable of reducing atmospheric pollution at the standards set by European legislation. The approach was implemented in the greater area of Thessaloniki and was part of a project aiming at the compliance with air quality standards in five major cities in Greece. The methodological approach comprises two stages: in the first stage, the availability of several measures contributing to a certain extent to reducing atmospheric pollution indicates a combinatorial problem and favors the use of Integer Programming. More specifically, Multiple Objective Integer Programming is used in order to generate alternative efficient combinations of the available policy measures on the basis of two conflicting objectives: public expenditure minimization and social acceptance maximization. In the second stage, these combinations of control measures (i.e., the control strategies) are then comparatively evaluated with respect to a wider set of criteria, using tools from Multiple Criteria Decision Analysis, namely, the well-known PROMETHEE method. The whole procedure is based on the active involvement of local and central authorities in order to incorporate their concerns and preferences, as well as to secure the adoption and implementation of the resulting solution. [ABSTRACT FROM AUTHOR]