P. T. Nastos

Acute effects of air pollution on pediatric asthma exacerbation: Evidence of association and effect modification

We investigated the short-term effects of particulate matter with aerodynamic diameter <10 μg/m(3) (PM(10)), sulfur dioxide (SO(2)), nitrogen dioxide (NO(2)) and ozone (O(3)) on pediatric asthma emergency admissions in Athens, Greece over the period 2001-2004. We explored effect modification patterns by season, sex, age and by the presence of desert dust transported mainly from the Sahara area. We used daily time-series data provided by the childrens hospitals and the fixed monitoring stations. The associations were investigated using Poisson regression models controlling for seasonality, weather, influenza episodes, day of the week and holiday effects. A 10 μg/m(3) increase in PM(10) was associated with a 2.54% increase (95% confidence interval (CI): 0.06%, 5.08%) in the number of pediatric asthma hospital admissions, while the same increase in SO(2) was associated with a 5.98% (95% CI: 0.88%, 11.33%) increase. O(3) was associated with a statistically significant increase in asthma admissions among older children in the summer. Our findings provide limited evidence of an association between NO(2) exposure and asthma exacerbation. Statistically significant PM(10) effects were higher during winter and during desert dust days, while SO(2) effects occurred mainly during spring. Our study confirms previously reported PM(10) effects on emergency hospital admissions for pediatric asthma and further provides evidence of stronger effects during desert dust days. We additionally report severe effects of SO(2), even at todays low concentration levels.

The effect of air temperature and human thermal indices on mortality in Athens, Greece

This paper investigates whether there is any association between the daily mortality for the wider region of Athens, Greece and the thermal conditions, for the 10-year period 1992–2001. The daily mortality datasets were acquired from the Hellenic Statistical Service and the daily meteorological datasets, concerning daily maximum and minimum air temperature, from the Hellinikon/Athens meteorological station, established at the headquarters of the Greek Meteorological Service. Besides, the daily values of the thermal indices Physiologically Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI) were evaluated in order to interpret the grade of physiological stress. The first step was the application of Pearson’s χ2 test to the compiled contingency tables, resulting in that the probability of independence is zero (p = 0.000); namely, mortality is in close relation to the air temperature and PET/UTCI. Furthermore, the findings extracted by the generalized linear models showed that, statistically significant relationships (p < 0.01) between air temperature, PET, UTCI and mortality exist on the same day. More concretely, on one hand during the cold period (October–March), a 10°C decrease in daily maximum air temperature, minimum air temperature, temperature range, PET and UTCI is related with an increase 13%, 15%, 2%, 7% and 6% of the probability having a death, respectively. On the other hand, during the warm period (April–September), a 10°C increase in daily maximum air temperature, minimum air temperature, temperature range, PET and UTCI is related with an increase 3%, 1%, 10%, 3% and 5% of the probability having a death, respectively. Taking into consideration the time lag effect of the examined parameters on mortality, it was found that significant effects of 3-day lag during the cold period appears against 1-day lag during the warm period. In spite of the general aspect that cold conditions seem to be favourable factors for daily mortality, the air temperature and PET/UTCI exceedances over specific thresholds depending on the distribution reveal that, very hot conditions are risk factors for the daily mortality.

Identification of aerosol type over the Arabian Sea in the premonsoon season during the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB)

A discrimination of the different aerosol types over the Arabian Sea (AS) during the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB-06) is made using values of aerosol optical depth (AOD) at 500 nm (AOD500) and A ngstrA¶m exponent (I±) in the spectral band 340-1020 nm (I±340-1020). For this purpose, appropriate thresholds for AOD500 and I±340-1020 are applied. It is shown that a single aerosol type in a given location over the AS can exist only under specific conditions while the presence of mixed aerosols is the usual situation. Analysis indicates that the dominant aerosol types change significantly in the different regions (coastal, middle, and far) of AS. Thus the urban/industrial aerosols are mainly observed in coastal AS, the desert dust particles occur in the middle and northern AS, while clear maritime conditions mainly occur in far AS. Spectral AOD and A ngstrA¶m exponent data were analyzed to obtain information about the adequacy of the simple use of the A ngstrA¶m exponent and spectral variation of a for characterizing the aerosols. Using the least squares method, I± is calculated in the spectral interval 340-1020 nm along with the coefficients a1 and a2 of the second-order polynomial fit to the plotted logarithm of AOD versus the logarithm of wavelength. The results show that the spectral curvature can effectively be used as a tool for their discrimination, since the fine mode aerosols exhibit negative curvature, while the coarse mode particles exhibit positive curvature. The correlation between the coefficients a1 and a2 with the A ngstrA¶m exponent, and the atmospheric turbidity, is further investigated.

Rainwater composition in Athens, Greece

Wet precipitation-only samplers were used to collect wet deposition at two sites in the Athens basin, Greece for the period March 1986–February 1987. Concentrations of major cations (H+, NH+4, Na+, K+, Ca2+ and Mg2+) and major anions (Cl−, NO−3 and SO2−4) were determined for the first time in rainwater samples in Greece. Bicarbonate concentrations were calculated. The relative importance of natural and anthropogenic sources were estimated by a chemical balance. The majority of rain collected has a neutral or alkaline character. Acidity was due to the presence of H2SO4 and HNO3. The statistical analysis of the correlation between the concentration of chemical species confirm the influence of natural and anthropogenic sources. In all samples, SO2−4 concentrations exceed NO−3 concentrations despite the dominance of low S oil burning in the region. The wet flux of S was calculatd to be 0.34 gm−2a−1.

Meteorological Patterns Associated with Intense Saharan Dust Outbreaks over Greece in Winter

The Mediterranean Basin and southern Europe are often affected by Saharan dust outbreaks, which influence the aerosol load and properties, air quality standards, visibility and human health. The present work examines, mainly of the meteorological point of view, three intense dust outbreaks occurred over Greece with duration of one or two days, on 4 and 6 February and 5-6 March 2009. The synoptic analysis on the dusty days showed the presence of low-pressure systems in the west coasts of Europe and the north Tyrrhenian Sea, respectively, associated with a trough reaching the north African coast. The result of these conditions was the strong surface and mid troposphere winds that carried significant amounts of dust over Greece. During the dusty days extensive cloud cover associated with the dust plume occurred over Greece. The air-mass trajectories showed a clear Saharan origin in all atmospheric levels, while the satellite (MODIS Terra/Aqua) observations as well as the model (DREAM) predictions verified the intense dust outbreaks over eastern Mediterranean and Greece. The ground based particulate matter concentrations in Athens were excessively increased on the dusty days (PM10: 150–560 μg/m3), while significant dry and wet deposition occurred as forecasted by DREAM model.

Air temperature trends related to changes in atmospheric circulation in the wider area of Greece

Surface air temperature trends in the wider region of Greece during the period 1951–2007, related to atmospheric circulation, are examined in this work. A network of 31 meteorological stations in the Hellenic area and the Asia Minor coasts and National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis datasets were used for this purpose. The NCEP/NCAR reanalysis datasets were created by assimilating climate observations from different sources including ships, satellites, ground stations, radiosonde observations and radar. The general purpose of conducting the reanalyses was to produce multiyear global state-of-the-art gridded representations of atmospheric states, generated by a constant model and a constant data assimilation system. The findings of the analysis show that the mean annual surface air temperature in the wider region of Greece exhibits a pronounced cooling trend from the beginning of the 1950s up to the mid-1970s. It then remained at low levels until the beginning of the 1990s, and then increased up to 2000, when a turning-point is clear although the temperature remained at high levels. The well-known atmospheric circulation indices of the wider region of Europe, namely the North Atlantic Oscillation Index (NAOI), the Mediterranean Oscillation Index (MOI) and the North Sea Caspian Pattern Index (NCPI), were used to investigate the relationship between surface air temperature and atmospheric circulation in this region of the Eastern Mediterranean. The surface air temperature is not correlated to the NAOI, while it is statistically significantly (95% confidence level (CL)) correlated to the MOI, but only during wintertime. On the contrary, good correlations, which are statistically significant (95% CL), appear between the NCPI and the surface air temperature during all seasons, but particularly in winter.

The Effect of Weather Variability on Pediatric Asthma Admissions in Athens, Greece

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 Childrens 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.

Assessment of bioclimatic conditions on Crete Island, Greece

The objective of this study was to assess and analyze the human bioclimatic conditions of Crete Island, by applying two human thermal indices: physiological equivalent temperature (PET), derived from the Munich Energy-balance Model for Individuals human energy balance model, and Universal Thermal Climate Index (UTCI), based on the Fiala multi-node model of human thermoregulation. Human bioclimatic studies provide a framework for considering the effects of climatic conditions on human beings and highlighting the social/economic factors that mitigate or amplify the consequences of environmental changes. In order to estimate the thermal effect of the environment on the human body, it has been considered that the total effects of all thermal components, not only of individual parameters, should be taken into account. The climatic data (air temperature, relative humidity, cloudiness, wind speed) used in this study were acquired from the archives of the Hellenic National Meteorological Service, regarding ten meteorological stations in Crete Island. These data, covering the 30-year period 1975–2004, were used for the calculation of PET and UTCI in order to assess thermo-physiological stress levels. The findings of this analysis, such as bioclimatic diagrams, temporal and spatial distributions of PET and UTCI as well as trends and variability, will help stake holders to understand and interpret the island’s current bioclimate, in order to make any necessary adaptations and become more resilient to the foreseen climate change.

Environmental impacts on human health during a Saharan dust episode at Crete Island, Greece

The objective of this study is to examine the relationship of the environmental variability (weather and particulate air pollution conditions) with cardiovascular and respiratory syndromes, in Heraklion city at the northern part of Crete Island, during a Saharan dust episode on March, 22-23 2008. Daily counts of admissions for cardiovascular and respiratory syndromes were obtained from the two main hospitals in Heraklion. The corresponding daily meteorological parameters, such as maximum and minimum air temperature, relative humidity, wind speed, cloudiness and atmospheric pressure, from the meteorological station of Heraklion (Hellenic National Meteorological Service), were manipulated in multivariate analyses. Besides, the bioclimatic conditions expressed by the Physiologically Equivalent Temperature (PET), based on the energy balance models of the human body, are analyzed. Dust concentrations were derived from the SKIRON forecast model of the University of Athens. The findings showed that the respiratory admissions were 3-fold than the mean daily admissions on the same day of the emergence of the Saharan dust episode (key day). The admissions concerning the cardiovascular syndromes did not appear any significant change. The analysis of the bioclimatic conditions on the key day revealed that thermal stress existed and this may be attributed mainly to the geomorphology of the island which is responsible for extreme weather conditions.

Human Bioclimatic Conditions, Trends, and Variability in the Athens University Campus, Greece

The objective of this work is the assessment of human thermal bioclimatic conditions in the Athens University Campus (AUC), including the Faculties and their respective Departments of the largest state institution of higher learning in Greece, and among the largest universities in Europe. The analysis of bioclimate was carried out, using the physiologically equivalent temperature (PET), which is based on the energy balance model of the human body. The meteorological data required for the calculation of PET concern hourly values of air temperature, relative humidity, wind speed and total solar radiation, for the time period 1999–2007. The recorded data sets were obtained from the meteorological station of the Laboratory of Climatology and Atmospheric Environment of the University of Athens. The results revealed the hours of the day in which thermal comfort or stress prevails, as well as the trends and variability of PET, for the studied period. Finally, the intense heat waves occurred during summer 2007 along with extreme cold conditions during December 2003-February 2004 were analyzed in terms of PET classes and compared to the respective average bioclimatic conditions of the study period.