Publications by Year: 2008

Nastos, P.T. & Matzarakis, A.P. Variability of tropical days over Greece within the second half of the twentieth century. Theoretical and Applied Climatology 93, 75 - 89 (2008). Publisher's VersionAbstract
Tropical days (TD) are defined as the days with a maximum air temperature greater than 30.0°C. It is clear that the study of TD includes also the absolute maximum temperatures, which are of great interest for the description of a region's climate. These days are considered as very hot, and they particularly are of great importance not only for bioclimatology and applied sciences, but also for the individuals who are sensitive in the heat-stress. The regime of the TD in Greece is the focus of this study. The aim is to demonstrate their changes from decade to decade, for the time period 1960-2000. For this study, the Annual Number of Tropical Days (ANTD) recorded by each of the 26 meteorological stations of National Meteorological Service, which are uniformly distributed in the Hellenic peninsula, was calculated and analysed. In terms of quantifying the conditions in a human-biometeorological manner, the thermal index Physiological Equivalent Temperature (PET) and the consecutive days for Athens have been included in this study. The trends of the TD for each station were analysed through the Mann-Kendall technique, while the spatial distribution per decade reveals the regions with change (increase or decrease) in the ANTD during the examined period. Two characteristic periods of change for the ANTD appear in the majority of the meteorological stations in Greece. The first period (1955-1976) is determined by a negative trend, which is statistically significant (c.l. 95%), for adequate stations. In the period between 1976 and 2000, the increase in the ANTD and the maximum temperature exceed the corresponding maximum that appeared in the beginning of the 1950s for several of the examined meteorological stations. The human-biometeorological analysis shows that the consecutive days of PET >35°C have had a positive trend in the last two decades of the last century. © Springer-Verlag 2007.
Nastos, P.T. & Zerefos, C.S. Decadal changes in extreme daily precipitation in Greece. Advances in Geosciences 16, 55 - 62 (2008). Publisher's VersionAbstract
The changes in daily precipitation totals in Greece, during the 45-year period (1957–2001) are examined. The precipitation datasets concern daily totals recorded at 21 surface meteorological stations of the Hellenic National Meteorological Service, which are uniformly distributed over the Greek region. First and foremost, the application of Factor Analysis resulted in grouping the meteorological stations with similar variation in time. The main sub groups represent the northern, southern, western, eastern and central regions of Greece with common precipitation characteristics. For representative stations of the extracted sub groups we estimated the trends and the time variability for the number of days (%) exceeding 30 mm (equal to the 95% percentile of daily precipitation for eastern and western regions and equal to the 97.5% percentile for the rest of the country) and 50 mm which is the threshold for very extreme and rare events. Furthermore, the scale and shape parameters of the well fitted gamma distribution to the daily precipitation data with respect to the whole examined period and to the 10-year sub periods reveal the changes in the intensity of the precipitation.
Nastos, P.T., Paliatsos, A.G., Papadopoulos, M., Bakoula, C. & Priftis, K.N. The effect of weather variability on pediatric asthma admissions in Athens, Greece. Journal of Asthma 45, 59 - 65 (2008). Publisher's VersionAbstract
The aim of this study was to determine whether there is any association between weather variability and asthma admissions among children in Athens, Greece. Medical data were obtained from hospital registries of the three main Children's Hospitals in Athens during the 1978-2000 period; children were classified into two age groups: 0-4 and 5-14 years. The application of Generalized Linear Models with Poisson distribution revealed a significant relationship among asthma hospitalizations and the investigated parameters, especially for the children aged 0-4 years. Our findings showed that Hospital admissions for childhood asthma in Athens, Greece, is negatively correlated with discomfort index, air temperature and absolute humidity whereas there is a positive correlation with cooling power, relative humidity and wind speed. Copyright © 2008 Informa Healthcare USA, Inc.
Nastos, P.T. Weather, ambient air pollution and bronchial asthma in Athens, Greece. Seasonal forecasts, climatic change and human health 173–188 (2008).Abstract
The associations between various meteorological parameters, concentrations of PM10, SO2, and O3 pollutants and bronchial asthma of residents of the wider region of Athens are examined in this study. For this purpose, 1,288 patients’ admissions (412 males and 876 females) recorded in 13 pneumonological clinics of Sotiria Hospital, which is the major Hospital for respiratory diseases in Athens, were analyzed for the period 1/1/2001–31/12/2002. The meteorological data were available by the National Observatory of Athens and the concentrations of PM10, SO2, and O3 pollutants were obtained by the air pollution network of 10 stations of the Ministry of Environment (Directorate of Air and Noise pollution Control).The evaluation of the possible relationship between the bronchial asthma admissions (BAA) and the meteorological variables was achieved by the application of Generalized Linear Models with Poisson distribution, because the medical dataset presents large divergence from a Gaussian distribution. The results showed that a statistically significant (p < 0.01) negative correlation between all examined air temperature variables, water vapor pressure, evaporation, sunshine, total solar irradiance, and BAA exists. Moreover, the findings of the analysis showed that a statistically significant relationship between the examined pollutants and BAA on the same day does not exist, with the exception of O3, which is correlated negatively (p < 0.01) with BAA. Nevertheless, there is a statistically significant lag effect (7–8 days) between the increase in BAA and the peak in the concentrations of PM10, SO2, and O3 pollutants. During the cold period of the year (October–April), BAA is significantly associated with O3 lag 2 day. The interannual variation of bronchial asthma admissions (BAA) reveals peaks within the transitional seasons of the year (spring and autumn), while the main minimum is apparent during summer period and especially in August.
Matzarakis, A. & Nastos, P.T. Heat waves in Athens. Proceedings of the 8th Hellenic Conference on Meteorology, Climatology and Atmospheric Physics 3, 153–160 (2008).
Nastos, P.T., et al. Wet deposition in two greek sites: Larissa and Athens. Fresenius Environmental Bulletin 17, 1648 - 1654 (2008). Publisher's VersionAbstract
The determination of the chemical composition of rainfall related to the origin of the air masses, in two urban sites in Greece during the year 2006, is investigated in this study. Two model automatic rain samplers were installed, the first in the city of Larissa, Thessaly, central Greece and the second in Heraklio, Attica, a northern suburb of Athens. The concentrations (ppm) of the major cations (H+, Na+, K+, Ca2+, NH4+ and Mg2+) and major anions (NO 3-, NO2-, HCO3 -, and SO42-), as well as total hardness (ppm CaCO3), pH and electric conductivity in 25°C (μS/cm) for 27 rainfall samples -11 samples in Larissa and 16 samples in Heraklio (Athens)- were determined. In Larissa, the figures of pH range from 5.13 to 6.13 while in Heraklio (Athens), the pH within the range 5.62 to 7.88 indicates a shift of the rainfalls towards alkalinity. The electric conductivity in Larissa ranges from 16.30 μS/cm to 110.60 μS/cm and in Heraklio (Athens) from 7.00 μS/cm to 151.00 μS/cm. The analysis showed that Ca2+ and Mg2+ appear the highest concentrations out of the examined cations, while HCO 3- and SO42- present the highest concentrations within the anions. Moreover, in order to find out the origin of the air masses, the air mass back trajectories were calculated using the HYSPLIT 4 model of Air Resources Laboratory of NOAA for two different levels: 1500 and 3000 m (a.m.s.l.). © by PSP 2008.
Nastos, P.T. & Matzarakis, A. Human-biometeorological effects on sleep disturbances in Athens, Greece: A preliminary evaluation. Indoor and Built Environment 17, 535 - 542 (2008). Publisher's VersionAbstract
The aim of this study was to examine the effects of the daily minimum air temperature and human-biometeorological variables, as well as their day-to-day changes, on sleep disturbances (SD) in the inhabitants of Athens, Greece. The SD dataset used for the analysis included the daily records of the psychiatric emergency unit of the Athens University Medical School for the years 1989 (with mild thermal load) and 1994 (with heavy thermal load). The meteorological variables for the estimation of the thermal indices were recorded by the meteorological station of Hellenikon, which is located at the headquarters of the Hellenic National Weather Service. The mean radiant temperature (T mrt) and the thermal indices predicted mean vote (PMV), physiologically equivalent temperature (PET) and standard effective temperature (SET*) have been analyzed. The first step was to assess the SD frequencies as a function of the meteorological and human-biometeorological variables on the basis of 10-day intervals to determine the influence of the examined variables on SD. The daily SD records were included as Poisson random variables in the applied Generalized Linear Models (GLM). The extracted results suggested that a considerable increase in SD existed in 1994 compared to 1989. This was due to the many consecutive days with heavy thermal load (PET >35°C and Tmin >23°C) in 1994 compared to the lack of such days in 1989. Furthermore, statistically significant (p<0.01) positive relationships were found between minimum air temperature, all thermal indices and SD. © SAGE Publications 2008.
Nastos, P.T., Paliatsos, A.G. & Priftis, K.N. Do the maxima of air pollutants coincide with the incidence of childhood asthma exacerbations in Athens, Greece?. Global Nest Journal 10, 453 - 460 (2008). Publisher's VersionAbstract
In the present study an assessment of the influence of the ambient air pollution on the incidence of the Childhood Asthma Admissions (CAA) is attempted by using cross spectrum analysis. The medical data concern the hospital registries of the three main Children's Hospitals of Athens for the 14-year period, 1987-2000. The air pollution data used in this study were mean monthly concentrations of CO, Black Smoke (BS), NOx, SO2, and O3, averaged over all the available stations, for each air pollutant, in the network of the Greek Ministry of the Environment, Physical Planning and Public Works (GMEPPPW) for the aforementioned 14-year period. The performed analysis revealed that a pronounced seasonal variation of asthma exacerbation among Athenian children does exist, rising during the cold damp period in pre-schoolers and peaking around May in the schoolchildren. We found that asthma admissions are associated with ambient air pollution at different frequencies. Asthma exacerbation among the first age group (0-4 years) is strongly depended on winter air pollution whereas older children (5-14 years) appear to be more vulnerable to the exposure of primary air pollutants mainly during late spring. Our findings strengthen the aspect that weather conditions such as sea breeze, mainly happen at the late spring or early summer in association with air pollution episodes could affect childhood asthma exacerbation. © 2008 Global NEST Printed in Greece. All rights reserved.
Kaskaoutis, D.G., Kambezidis, H.D., Nastos, P.T. & Kosmopoulos, P.G. Study on an intense dust storm over Greece. Atmospheric Environment 42, 6884 - 6896 (2008). Publisher's VersionAbstract
Springtime constitutes the most favorable period for Sahara dust outbreaks and transport over Eastern Mediterranean. This study investigates the aerosol properties during April 2005 using remote-sensing and ground-based measurements. Three dust events with high aerosol optical depth (AOD) values have been observed during the measuring period, with duration of two days, i.e. 11-12, 16-17 and 25-26 April 2005. In this paper we mainly focus on the intense dust event of 16-17 April 2005, when a thick dust layer transported from Libya affected the whole Greek territory. Very high AOD values obtained from Aqua-MODIS sensor were observed over Greece (mean 2.42 ± 1.25) on 17 April, while the respective mean April value was 0.31 ± 0.09. The AOD at 550 nm (AOD 550) values over Crete were even larger, reaching ∼4.0. As a consequence, the PM 10 concentrations over Athens dramatically increased reaching up to 200 μg m -3. On the other hand, the fine-mode fraction values obtained from Terra-MODIS showed a substantial decrease in the whole Greek area on 17 April with values below 0.2 in the Southern regions. The intense dust layer showed a complex behavior concerning its spatial and temporal evolution and allowed us to study the changes in the optical properties of the desert dust particles along their transport routes due to the mixing processes with other aerosol types. The results from different measurements (ground-based and remote-sensing) did not contradict each other and, therefore, are adequate for monitoring of dust load over the Eastern Mediterranean. © 2008 Elsevier Ltd. All rights reserved.
Philandras, C.M., Nastos, P.T. & Repapis, C.C. Air temperature variability and trends over Greece. Global Nest Journal 10, 273 - 285 (2008). Publisher's VersionAbstract
In this study, the variability and trends of the mean annual and seasonal surface air temperature in Greek peninsula are examined. The climatic data used, concern mean monthly values of air temperature of 20 meteorological stations of the Hellenic Meteorological Service, for the period 1951-2000. The air temperature time series for each station are analyzed, so that the variability and trends be described. Regarding the annual time series, a cooling trend is observed since the early 1960's till the middle of the decade of 1970, when the trend reverses to heating till nowadays. It is remarkable that the today air temperature levels do not exceed the levels of the middle of the century. During the winter, it is crystal clear that a cooling trend exists from the middle of the decade of 1950 to the end of the decade of 1980, especially in the south region of the country. Afterwards an increasing trend is obvious till nowadays. The pattern in spring appears a slight heating trend in the northern region of Greece and a cooling trend in the south. The summer time series are similar to the annual ones, so the contribution of summer to annual variability is unquestionable. Generally speaking, the air temperature in autumn follows the same distribution in time. In the process, the Factor Analysis is applied on the mean annual and seasonal air temperature and thereafter the regions, within the air temperature covariates, are defined. Finally, the application of spectral analysis to annual and seasonal air temperature is regarded necessary so that the periodicities are derived. © 2008 Global NEST Printed in Greece. All rights reserved.
Kosmopoulos, P.G., Kaskaoutis, D.G., Nastos, P.T. & Kambezidis, H.D. Seasonal variation of columnar aerosol optical properties over Athens, Greece, based on MODIS data. Remote Sensing of Environment 112, 2354 - 2366 (2008). Publisher's VersionAbstract
A long-term (2000–2005) data set of aerosol optical properties obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) is analyzed focusing on the Greater Athens Area in the Eastern Mediterranean region. The MODIS aerosol optical depth standard product (AOD at 550 nm) and its respective ratio attributed to fine-mode particles (FM) are employed to evaluate the inter-annual and seasonal variability of the aerosol properties over Athens. Based on AOD550 and FM values three specific aerosol types are discriminated corresponding to different aerosol load and optical properties. The aerosol types considered correspond to urban/industrial aerosols, coarse-mode particles and clean maritime conditions. This study focuses on the seasonal and year-to-year fluctuation of the number of occurrences as well as the AOD550 and FM values of each aerosol type. The coarse-mode particles are observed mainly in the summer, while spring is the most favorable season for the occurrence of urban/industrial aerosols. On the other hand, clean maritime conditions occur mainly in the winter. The AOD550 values for the coarse-mode particles are higher in spring, while the urban/industrial and clean maritime aerosols exhibit slightly higher values in the summer. The seasonal distribution of the aerosol properties is related to anthropogenic and dust emissions in the spring/summer period, but is modified by atmospheric dispersion and precipitation in late autumn/winter. The main conclusion of the study is that the coarse-mode particles exhibit much stronger interannual and seasonal variability compared to the urban/industrial aerosols. Finally, three cases corresponding to each aerosol type are analyzed with the aid of synoptic weather maps, air mass trajectories and MODIS data.
Grigoropoulos, K.N., et al. Spatial distribution of PM1 and sinus arrhythmias in Athens, Greece. Fresenius Environmental Bulletin 17, 1426 - 1431 (2008). Publisher's VersionAbstract
The study of particulate matter with diameter less than 1 μm (PM 1) in Athens' atmosphere and their impacts on human health is the goal of this study. PM1 concentrations were recorded by three detectors (light scattering method) at six vital points in high traffic peak roads, during the period 1/10/2006-30/9/2007. The collected PM1 samples concern the same hour of the day, in absence of wind. The spatial distributions of the PM1 concentrations for the warm (April to September) and the cold (October to March) period of the year were achieved by the use of Kriging method. Further to, in order to find out the impacts of PM1 concentrations on health, we analyzed daily admissions for non-fatal arrhythmias to emergency units of the Social Security Institute and a Regional Hospital of Athens. Results demonstrate a significant relationship of PM1 with sinus arrhythmias, which confirms the assumption that PM1 represent one of the main hazards in cardio respiratory syndromes in the most polluted cities of Europe, which confront high traffic problems, due to the enormous number of exhausts emissions.
Vasilakou, M., et al. Lack of association between endothelial nitric oxide synthase gene polymorphisms and risk of premature coronary artery disease in the Greek population. Acta Cardiologica 63, 609 - 614 (2008). Publisher's VersionAbstract
Objective - Genetic polymorphisms in the gene for endothelial nitric oxide synthase have been considered as potential risk factors for the development of coronary artery disease in some populations. Methods - We studied two polymorphisms of the NOS3 gene, the VNTR in intron 4 (4VNTR) and the Glu298Asp polymorphism in exon 7, in relation to the existence of premature coronary artery disease and the occurrence of myocardial infarction. A total number of 370 individuals of the Greek population was examined by PCR-RFLP method. The patient group consisted of 209 subjects, aged less than 58 years presenting symptomatic coronary artery disease, documented by coronary angiography. Results - The frequencies for bb, ab and aa genotypes of 4VNTR polymorphism were 0.67, 0.29, 0.04, respectively, for the patient group and 0.73, 0.24, 0.03 for the control group. The frequencies for GG (Glu/ Glu), GT (Glu/Asp), TT (Asp/Asp) of the Glu298Asp polymorphism were 0.52, 0.41, 0.07, respectively, in patients compared to 0.47, 0.46, 0.07, in control subjects. Statistical analysis indicated that there are no significant differences in the frequencies of the genotypes between patients and control subjects for both polymorphisms. The combined analysis of the two polymorphisms indicated no synergistic effect of the a and T alleles on coronary artery disease. Conclusions - We have found no evidence for association between the a allele of the 4VNTR polymorphism, or the T allele of Glu298Asp polymorphism and the risk for premature coronary artery disease or occurrence of myocardial infarction. Furthermore, no synergistic contribution of these polymorphisms to the development of premature coronary artery disease has been observed.