Efstratios Vogiannis

Modelling of radon concentration peaks in thermal spas: Application to Polichnitos and Eftalou spas (Lesvos Island--Greece)

A mathematical model was developed for the description of radon concentration peaks observed in thermal spas. Modelling was based on a pragmatic mix of estimation and measurement of involved physical parameters. The model utilised non-linear first order derivative mass balance differential equations. The equations were described and solved numerically by the use of specially developed computer codes. To apply and check the model, measurements were performed in two thermal spas in Greece (Polichnitos and Eftalou-Lesvos Island). Forty different measurement sets were collected to estimate the concentration variations of indoor-outdoor radon, radon in the entering thermal water, the ventilation rate, the bathtub surface and the bath volume. Turbulence and diffusive phenomena involved in radon concentration variations were attributed to a time varying contact interfacial area (equivalent area). This area was approximated with the use of a mathematical function. Other model parameters were estimated from the literature. Through numerical solving and use of non-linear statistics, the time variations of the equivalent area were estimated for every measurement set. Computationally applied non-linear uncertainty analysis showed less sensitive variations of the coefficients of the equivalent area compared to parameters of the model. Modelled and measured radon concentration peaks were compared by the use of three statistical criteria for the goodness-of-fit. All the investigated peaks exhibited low error probability (***p<0.001) for all criteria. It was concluded that the present modelling achieved to predict the measured radon concentration peaks. Through adequate selection of model parameters the model may be applied to other thermal spas.

Radon Sources and Associated Risk in Terms of Exposure and Dose

Radon concerns the international scientific community from the early twentieth century, initially as radium emanation and nearly the second half of the century as a significant hazard to human health. The initial brilliant period of its use as medicine was followed by a period of intense concern for its health effects. Miners in Europe and later in the U.S were the primary target groups surveyed. Nowadays, there is a concrete evidence that radon and its progeny can cause lung cancer (1). Human activities may create or modify pathways increasing indoor radon concentration compared to outdoor background. These pathways can be controlled by preventive and corrective actions (2). Indoor radon and its short-lived progeny either attached on aerosol particles or free, compose an air mixture that carries a significant energy amount [Potential Alpha-Energy Concentration (PAEC)]. Prior research at that topic focused on the exposure on PAEC and the dose delivered by the human body or tissues. Special mention was made to the case of water workers due to inadequate data. Furthermore, radon risk assessment and relevant legislation for the dose delivered by man from radon and its progeny has been also reviewed.

Investigation of the exposure to radon and progeny in the thermal spas of Loutraki (Attica-Greece): Results from measurements and modelling

Radon and progeny ((218)Po, (214)Pb, (214)Bi and (214)Po) in thermal spas are well known radioactive pollutants identified for additional radiation burden of patients due to the activity concentration peaks which appear during bath treatment or due to drinking of waters of high radon content. This burden affects additionally the working personnel of the spas. The present paper has focused on the thermal spas of Loutraki (Attica-Greece). The aim was the investigation of the health impact for patients and working personnel due to radon and progeny. Attention has been paid to radon and progeny transient concentration peaks (for bath treatment) and to radon of thermal waters (both for bath treatment and drinking therapy). Designed experiments have been carried out, which included radon and progeny activity concentration measurements in thermal waters and ambient air. Additionally, published models for description of radon and progeny transient concentration peaks were employed. The models were based on physicochemical processes involved and employed non linear first order derivative mass balance differential equations which were solved numerically with the aid of specially developed computer codes. The collected measurements were analysed incorporating these models. Results were checked via non linear statistical tests. Predictions and measurements were found in close agreement. Non linear parameters were estimated. The models were employed for dosimetric estimations of patients and working personnel. The effective doses of patients receiving bath treatment were found low but not negligible. The corresponding doses to patients receiving potable treatment were found high but below the proposed international limits. It was found that the working personnel are exposed to considerable effective doses, however well below the acceptable limits for workers. It was concluded that treatment and working in the Loutraki spas leads to intense variations of radon and progeny and consequently additional health impact both to patients and working personnel.

Factors Affecting Indoor Radon Concentrations of Greek Dwellings through Multivariate Statistics - First Approach

A large scale nationwide radon survey was conducted in Greek dwellings between 1994 and 2000. Twelve hundred passive CR-39 detectors were distributed and collected along with 963 filled in questionnaires. These were rechecked during 2012-13 to evaluate factors that potentially affect indoor radon concentrations, namely the factors (i) area (environment), (ii) building level-floor, (iii) ground type, (iv) basement, (v) building type, (vi) construction year, (vii) building walls contact, (viii) wall materials and (ix) floor materials. The questionnaires were prepared by the research team according to international standards. One-way and multivariate statistical methods were applied for the analysis, in specific (I) Linear Regression Analysis, (II) One way or multiway ANOVA, (III) General MANOVA, (IV) Stepwise Regression Analysis and (V) Principal Components Analysis. The results revealed that approximately 0.1% of the dwellings exhibited outlier radon concentrations. Noteworthy statistical correlations were detected between the measured mean annual indoor radon concentration levels and the factors (ii) (building level-floor) and (viii) (wall materials). Weak evidence was provided for the corresponding correlation with the factors (v) (building type) and (vii) (building walls contact). Minor was the association with the factors (iv) (construction year) and (ix) (floor materials). Significant differences were detected in the results of the applied statistical methods.

Preliminary background indoor EMF measurements in Greece

The main purpose of this work was to investigate the fluctuation of Greek indoor electromagnetic field (EMF) intensity values and identify peaks that might occur. The scientific interest is mainly focused on the bands of extremely low-frequency (ELF) magnetic fields and radiofrequency (RF) electric fields which have been suggested to be possibly carcinogenic to humans by the Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR). Electromagnetic radiation (EMR) measurements were performed in a variety of indoor dwellings, in Attica and in the islands of Zakynthos and Lesvos. A total number of 4540 measurements were taken in a wide frequency range (50 Hz-2100 MHz) of which 3301 in Attica, 963 in Lesvos and 276 in Zakynthos. Statistical analysis of the data revealed specific statistically significant differences between the mean values of the electric (ELF and RF) but not the magnetic (ELF) field strengths measured at different distances from the EMF source, as well as between some of the mean values of the RF electric field at different bands. Some statistically significant differences between mean electric field values at different geographic locations were also identified. As far as the RF electric field is concerned, the maximum values, in most cases, were below 0.5 V/m, however increased values above 1 V/m and up to 5.6 V/m were occasionally observed. The ELF magnetic field values were lower than 1 μT. It may be concluded that overall, the observed indoor EMF intensity values remained well below domestic and European established limits.

Results of the simultaneous measurements of radon around the Black Sea for seismological applications

Results of measurements of radon around of the Black Sea are shown. Radon stations in zones of active faults were placed. Simultaneous hourly measurements of soil radon in 2005 were carried out in the Sivrice Fault Zone that is a segment of East Anatolian Fault System, in the town of Tbilisi (Georgia) and in the South Russia. In 2008 simultaneously hourly measurements of soil radon were carried out in the Western Caucasus (Russia) and in the Mytilene Island (Greece). In 2013 radon in underground waters simultaneously in midday was measuring in Crete (Greece), in the Pamukkale geothermal region (Southwest Turkey) and in the Western Caucasus. Measurements of radon concentration in the points located around of the Black Sea have shown identical regularities in changes of the data. Influence of meteorological, tidal and solar factors on changes of water radon concentrations and soil radon concentrations was observed in all researches points. But this influence was insignificant. Seismological application of observed results also was considered. Various mathematical methods of definition of anomaly in the radon data during earthquakes were considered. During researches in the Black Sea region basically earthquakes with M from 2.0 up to 5.0 and in a depth about 10 km were occurred. For these earthquakes method of daily subtraction of the data of the next and previous day was used. This method has allowed solving a problem with a choice of average value. Probability up to 0.69 (number of earthquakes with radon anomalies/total number of earthquakes) of detection of radon anomalies before earthquakes was achieved applying this method. Changes of radon maps before regional earthquakes were also observed. The frequency analysis of variations of the radon data on the basis of the Wavelet analysis was carried out. Occurrence of the short periods (about 2 days) was observed during regional earthquakes.

Pilot Electromagnetic Field Measurements in Certain Areas in Greece

This paper reports preliminary electromagnetic field measurements conducted indoors in selected locations in Greece. The paper focuses on the electromagnetic radiation (EMR) of the extremely low-frequency (ELF) and radiofrequency (RF) frequency bands because these bands are considered as possible human carcinogens according to the Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR). ELF electric and magnetic fields and RF electric fields were measured indoors in several locations in urban, suburban and rural areas of the Zakynthos and Lesvos islands, suburban houses of Ileia Prefecture (Peloponnisos) and urban dwellings of Attica. A total number of 4816 measurements were taken in Zakynthos (276), Lesvos (964), Ileia (29) and Attica (3547) in the frequency range 50 Hz–2500 MHz. Measurements were conducted with NARDA EMR-300 RF survey meter (3935), Aaronia HF and NF spectrum analyzers (795), HI 3604 Holaday ELF survey meter (48) and ANTENNESSA EME SPY (38). The maximum electric field strengths were in most cases below 5 V/m. Strength of electric fields up to 3000 V/m were addressed near high voltage power transmission lines. Stronger average electric fields were measured in urban areas. The strengths of the magnetic field were in most cases lower than 1000 nTesla (1 μTesla), but values up to 6000 nTesla (6 μTesla) were observed near high voltage power transmission lines. The results indicated that the EMR strength values varied but were all below domestic and international established limits.

How Safe is the Environmental Electromagnetic Radiation

The natural electromagnetic environment originates from the Earth (terrestrial sources) and from space (extraterrestrial sources). Compared with man-made fields, natural fields are extremely small, especially at the radiofrequency band. Electric and magnetic fields exist wherever electricity is generated, transmitted or distributed from power stations or used in electrical appliances. Since the use of electricity is an integral part of modern lifestyle, these fields are ubiquitous in the environment. The situation became ‘heavier’ with the impressive evolution of the mobile phone and telecommunication technology. The incident fields interact or couple with the human body and induce electric and magnetic fields and currents within the body tissues. Oscillating charges may be induced on the surface of the exposed body and these induce currents inside the body. A different interaction mechanism exists for the electric- and magnetic-field components. Dosimetry describes the relationship between the external fields and the induced electric field and current density in the body and the outcome serves as the basis on which authorities recommend limits for human exposure. The locally induced electric field and current density are of particular interest because they relate to the stimulation of excitable tissue such as nerve and muscle. The distribution of induced currents across the various organs and tissues is determined by the conductivity of those tissues. Many mechanisms, mainly when concerning thermal effects, become detectable only at fields above certain strength. Nevertheless, the lack of identified admissible mechanisms does not rule out the possibility of adverse health effects even at very low field levels, provided basic scientific principles are adhered to

Response of CR-39 Polymer Radon-Sensors via Monte-Carlo Modelling and Measurements

International studies of radon indoors and in workplaces have shown significant radiation dose burden of the general population due to inhalation of radon (222Rn) and its short-lived progeny (218Po,214Pb, 214Bi, 214Po). As far as atmospheric radon concerns, 222Rn, is not necessarily in equilibrium with its short-lived progeny. For this reason, radon’s equilibrium factor F was solved graphically as a function of the track density ratio R=TB/TR, namely of the ratio between the recordings of cup-type and bare CR-39 detectors. TB was computed through special Monte-Carlo codes which were implemented for the calculation of the efficiency of bare CR-39 polymers, regarding their ability in sensing the alpha particles emitted by the decay of radon and its short-lived progeny. For a realistic approach, Monte-Carlo inputs were adjusted according to actual experimental concentration measurements of radon, decay products and F of Greek apartment dwellings. Concentration measurements were further utilized for the calculation of the unattached fraction, fp, in terms of Potential Alpha Energy Concentration (PAEC, defined as the sum of the initial - per volume - energies of all alpha particles emitted due to the decay of radon and its short-lived progeny that are present within a certain amount of air). This was employed for the calculation of F in terms of ratio (A4/A0), where Ai represents the activity concentration of radon (i=0) and 214Po (i=4) respectively. Measured and calculated values of F were plotted versus R. The results were fitted and checked with model’s predictions.