| Summary: | The objective of this study is to examine the synergistic environmental impacts (thermal bioclimatic conditions and air quality due to particulate pollution) with cardiovascular and respiratory syndromes, in Heraklion in 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 and cloud cover, from the meteorological station of Heraklion (Hellenic National Meteorological Service), were processed in order to estimate and analyze the bioclimatic conditions expressed by the Physiologically Equivalent Temperature (PET), which is based on the energy balance models of the human body. Dust concentrations were derived from the SKIRON forecast model of the University of Athens, while Moderate Resolution Imaging Spectroradiometer (MODIS) products such as aerosol optical depth at 550 nm (AOD550), aerosol small mode fraction (SM), Ångström exponent in the 550-865 nm band and mass concentration, were used for the episode. Besides, daily composite anomalies (reference period: 1968-1996) of the air temperature and vector wind from the middle to the lower atmospheric levels (500 hPa - mean sea level) on March 23, 2008, were calculated from the reanalysis datasets of the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR). The analysis of MODIS and SKIRON products showed that high AOD550 values (>0.9) and high dust concentration (>250 μg/m3), respectively, appear on March 23, 2008, while the respiratory admissions were five-fold than the mean daily admissions on the same day of the emergence of the Saharan dust episode (key day). According to the analysis, this is due to the existence of coarse-mode particles along the dust pathway, which trigger respiratory syndromes more than cardiovascular, which are associated more with ultra-fine particles. The admissions concerning the cardiovascular syndromes did not appear any significant change. The analysis of the bioclimatic conditions on the key day revealed that moderate thermal stress existed and this may be attributed mainly to the geomorphology of the island, which is responsible for special weather conditions such as Föhn winds. The drier atmospheric conditions, as a result of strong, desiccating winds on the leeward side of the mountains, contribute more to the already high hospital admissions for respiratory symptoms.
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