Objective: To quantify the amount of Total Volatile Organic Compounds (TVOCs) emitted from five dental substances commonly used in a dental clinic. Method: An assessment of the indoor air quality in two clinics of the Athens University Dentistry Faculty was conducted. Results: It was found that TVOC emissions from Kalocryl and Bacillol reached extremely high values affecting the air in the dental clinics at short and long distances from the source. Six pollutants TVOCs, CO2, PM10, PM25, SO 2 and NOx were measured and indoor sources associated with dental activities were identified. Very high concentrations of TVOCs were found which exceeded the acceptable levels by a factor of 20, associated with the nature of the dental activities and the ventilation conditions. The CO 2 concentration levels were high and the indoor conditions were considered unsatisfactory, associated with the number of occupants and the ventilation conditions. PM concentrations were high due to the nature of the dental activities and they exceeded the outdoor levels by a factor of 5 to 6. The concentrations of the gaseous pollutants NOx were low while the SO 2 concentrations were hardly detectable. © 2008 FDI/World Dental Press.

Air quality in two large athletic halls with different ventilation (natural and mechanical) was investigated in relation to outdoor pollution and meteorological conditions. Simultaneous measurements of O3, NO, NO2 and SO2 were performed in the halls at two heights (at the arena and spectators’ seats) and outdoors. BTX concentrations at the spectators’ seats and outdoor NMHCs, CH4, PM10 and CO concentrations were also measured. Analysis of diurnal variations of the pollutants’ concentrations, cross correlation analysis of the concentration time-series and principal component analysis were applied to the collected data. Results revealed that outdoor pollution significantly affected indoor air quality of both halls. However, this effect was different for the two buildings, depending on the ventilation types, the wind direction prevailing at the areas and the kind of indoor activity recorded. It was found that the latter parameters controlled the pollutants concentration levels in the halls and their response to the changes of the outdoor pollution levels. Temperature and pollution stratification enhancing during athletic events were also evident in both halls but with different characteristics observed, such as the spatial distribution of the indoor pollutants. The airflow patterns prevailing in each hall, imposed by the ventilation operation schemes were important factors. © 2007 Elsevier Ltd. All rights reserved.

The aim of this study is to estimate future potential changes in duration of extreme dry and wet spells and rainfall intensity in Eastern Mediterranean. For this purpose, daily precipitation amounts, deriving from the regional climate model of UK Hadley Centre HadRM3P have been used for the present (1960-1990) and the future period 2070-2100 on 0.44° × 0.44° latitude by longitude grid. Future data are based on B2 IPCC emission scenario. For the identification of precipitation extremes three climatic indices were employed: a) CWD (Maximum number of consecutive wet days), b) CDD (Maximum number of consecutive dry days) and c) SDII (quotient of precipitation amount of wet days and the number of wet days of the period). They were calculated for the present and future period, on a seasonal and annual basis. A general future tendency was found towards drier Eastern Mediterranean, with reduced rainfall intensity. Longer dry spells are expected in all seasons, except autumn, with the largest increase in the southern part of the area. Extreme wet spells will shorten everywhere during all seasons, except autumn. Precipitation intensity was found reduced for all seasons and mostly for summer in South Aegean Sea. © 2008 Global NEST Printed in Greece. All rights reserved.

The objective of this study is to estimate the duration, frequency and intensity of precipitation extreme episodes in Cyprus, in relation with the two phases of the Eastern Mediterranean teleconnection Pattern (EMP), during winter for the period 1958–2005. A standardised teleconnection index was employed to determine the phases (positive and negative) and the strength of the EMP. The identification of the precipitation extremes was performed with the aid of four climatic indices. It was found that during the positive phase of the pattern, the length of dry periods reduces while that of wet periods increases, being followed by increase of frequency of extreme wet days and precipitation intensity. On the contrary, during the negative phase, the dry spells become longer in accordance with shortening of the wet spells, decrease of the number of extreme wet days and precipitation intensity.

Airborne particulate matter (PM10, PM2.5, PM1) and volatile organic compounds (benzene, toluene, m,p-xylene, o-xylene) samples were collected during winter and summer seasons of 2005 at two sites, representing an urban and a suburban region of the Greater Athens Area. Urban site traffic emissions were the major contributor to the concentration of PM2.5, PM10, toluene, and xylenes, while benzene and PM1 concentrations were presented in significant spatial variations. K+, Na+, Mg2+, Ca2+, NO3 -, Cl- and SO4 2 - ions were analyzed for the chemical characterization of the collected PM samples. The results showed that Na+ cations and SO4 2 - anions were the dominant species, during winter and summer, respectively, in both sites. The analysis of the synoptic scale and mesoscale atmospheric circulation during the experimental periods demonstrated that the meteorological conditions play a key role, not only in the variation but also in the distribution of the ionic concentrations at the three fractions of particulates and the dominant character (alkaline/acidic/neutral) of the particulates at the two sampling sites. © 2008 Elsevier Ltd. All rights reserved.

The capability of the general circulation model(GCM) Hadley Center atmospheric general circulation model 3P (HadAM3P) to reproduce the mean pattern and the frequency of circulation types concerning the 500 hPa geopotential height fields and 1000-500 hPa thickness fields over Europe and the Mediterranean region are evaluated against the NCEP/NCAR dataset for the period 1960-1990. Daily catalogues of the circulation types describing the regional circulation over Greece at the 500 hPa and 1000-500 hPa thickness fields are constructed based on the two datasets, and the corresponding seasonal frequencies are also estimated. The evaluation is performed for the mean seasonal fields of the two parameters, as well as for those derived for each circulation type separately. It is demonstrated that the HadAM3P model generally succeeds in reproducing the two fields over the examined area, while their seasonal variability is underestimated. The mean patterns of the circulation types are well represented by the model but the seasonal simulated frequencies of the circulation types are not in good agreement with the national centers for environmental predictions (NCEP) ones. The systematic errors of the frequency estimation and the variability in some anticyclonic or cyclonic types should be considered seriously, because it can introduce some degree of uncertainty in the results of a downscaling method based on a circulation type approach. Nevertheless, the links between the precipitation, temperature and circulation types frequency seem to hold in the GCMs. It is therefore safe to use the frequencies of circulation types as predictor in a downscaling technique in order to obtain future precipitation and temperature. Copyright © 2007 Royal Meteorological Society.

Significant changes in the regional climate of coastal and island stations in and bordering the Aegean during 1961-2002 are identified. Here we start with a very large number of parameters describing the surface temperature climate measured at 9 Greek island and coastal stations, and highlight those parameters which show regionally significant trends. Statistical significance of trends is assessed over multiple sliding time-windows of data. For each parameter and each time-window, a regional summary is produced using two quantities: the statistical significance of the trend in the regionally averaged parameter, and the number of stations which individually show significant trends in that parameter. The relationship between these two quantities provides a simple way of highlighting those climate parameters for which the region shows a trend, which is spatially relatively homogeneous, and those for which the region may need to be divided into sub-regions. Some very detailed characteristics of trends in daily surface temperatures are summarized in a concise way. Notably, the established cooling during the 1960s is shown to be especially strong for November and also December. Some trends were also shown to be significant only in terms of temperatures of unseasonably warm or cool days. For example, cooling in May temperatures in the late 70s/early 80s occurred most clearly for the low-temperature range-appearing as a decrease in the temperature reached by unseasonably cold days. This behaviour was inhomogeneous across the region, with significant cooling at only a subset of the stations. Such results could be used by subsequent analysis to focus on particular parts of the data, rather than using averaging to reduce the data. Copyright © 2008 Royal Meteorological Society.