Rome, Italy
Rome, Italy

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Franci D.,ARPA Lazio | Aureli T.,ARPA Lazio | Cardellini F.,Instituto Nazionale Of Metrologia Delle Radiazioni Ionizzanti Inmri
Radiation Protection Dosimetry | Year: 2016

Time-integrated measurements of indoor radon levels are commonly carried out using solid-state nuclear track detectors (SSNTDs), due to the numerous advantages offered by this radiation detection technique. However, the use of SSNTD also presents some problems that may affect the accuracy of the results. The effect of overlapping tracks often results in the underestimation of the detected track density, which leads to the reduction of the counting efficiency for increasing radon exposure. This article aims to address the effect of overlapping tracks by proposing an alternative calibration technique based on the measurement of the fraction of the detector surface covered by alpha tracks. The method has been tested against a set of Monte Carlo data and then applied to a set of experimental data collected at the radon chamber of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti, at the ENEA centre in Casaccia, using CR-39 detectors. It has been proved that the method allows to extend the detectable range of radon exposure far beyond the intrinsic limit imposed by the standard calibration based on the track density. © The Author 2016. Published by Oxford University Press. All rights reserved.


Silibello C.,ARIANET Srl | Bolignano A.,ARPA Lazio | Sozzi R.,ARPA Lazio | Gariazzo C.,Research Center
Air Quality, Atmosphere and Health | Year: 2014

The combined use of air quality monitoring data and state-of-the art dispersion models provides a more realistic representation of the spatial distribution of pollutants and allows a reduction in the uncertainties involved in the assessment of the exposure in epidemiological studies. Data assimilation is a method which combines such information to produce an optimal representation of the state of the atmosphere. In this work, we tested two approaches to merge these information sets: the successive corrections method (SCM) and the statistical optimal interpolation (OI). These methods have been extended in order to take into account the spatial representativeness of measurements. PM10, NO2, and O3 concentration fields produced by an air quality modeling system, run with two nested domains covering much of Central Italy and the Rome urban area, have been used to identify the optimal values for the horizontal and vertical scaling distances that are key parameters for the SCM and OI methods. A statistical analysis of the results obtained from the application of these methods demonstrated that lower RMSE values resulted from the use of the OI method. Further, PM2.5 modeling results over the Rome urban area and additional measurements collected during experimental campaigns, performed within the population exposure to polycyclic aromatic hydrocarbons (EXPAH) LIFE+ Project, allowed the evaluation of this approach in reconstructing PM2.5 levels at EXPAH monitoring sites, which were not used in the data assimilation process. The results confirmed the potential of these methods to improve the estimation of modeled concentrations, by taking into account local phenomena not resolved by the model, but clear from the observations, and also in providing more reliable data to be used in exposure studies. © 2014 Springer Science+Business Media Dordrecht.


Franci D.,ARPA Lazio | Aureli T.,ARPA Lazio
Radiation Protection Dosimetry | Year: 2014

Solid-state nuclear track detectors are commonly used for the detection of indoor radon levels. However, despite numerous advantages, this technique still presents many unsolved problems. An important source of error is represented by the reduction in the detection efficiency due to overlapping tracks, which results in a sensible underestimation of the radon levels. This paper presents a new experimental procedure to address the effect of overlapping tracks by establishing a relationship between the detection efficiency and the number of detected tracks. Experimental data have been collected at the radon chamber of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti (INMRI), at the ENEA centre in Casaccia, using CR-39 detectors provided by Radosys Ltd. It has been proved that the method, applied to the experimental settings of this study, gives reliable results up to 7607 kBq h m23. Finally, the method has been validated through a Monte Carlo simulation, exploring a wide range of radon exposure.


Franci D.,ARPA Lazio | Aureli T.,ARPA Lazio | Cardellini F.,ENEA
Radiation Protection Dosimetry | Year: 2015

The aim of this study was to investigate the effect of ageing and fading on PADC detector response, as a function of the storage time and temperature. Several groups of CR-39 detectors provided by Radosys, Ltd. were exposed at the reference radon chamber of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti, at the ENEA centre in Casaccia. The results indicate that low-temperature storage inhibits the effect of both ageing and fading. Finally, the overall reduction in CR-39 sensitivity due to the combined ageing/fading effect was estimated. In particular, the sensitivity of the detectors continuously exposed in air at room temperature over 6 and 3 months was reduced, respectively, by 7.5 and 4 %. © The Author 2014.


Gariazzo C.,Research Center | Pelliccioni A.,Research Center | Bolignano A.,ARPA Lazio
Atmospheric Environment | Year: 2016

A dynamic city-wide air pollution exposure assessment study has been carried out for the urban population of Rome, Italy, by using time resolved population distribution maps, derived by mobile phone traffic data, and modelled air pollutants (NO2, O3 and PM2.5) concentrations obtained by an integrated air dispersion modelling system. More than a million of persons were tracked during two months (March and April 2015) for their position within the city and its surroundings areas, with a time resolution of 15 min and mapped over an irregular grid system with a minimum resolution of 0.26 × 0.34 Km2. In addition, demographics information (as gender and age ranges) were available in a separated dataset not connected with the total population one. Such BigData were matched in time and space with air pollution model results and then used to produce hourly and daily resolved cumulative population exposures during the studied period. A significant mobility of population was identified with higher population densities in downtown areas during daytime increasing of up to 1000 people/Km2 with respect to nigh-time one, likely produced by commuters, tourists and working age population. Strong variability (up to ±50% for NO2) of population exposures were detected as an effect of both mobility and time/spatial changing in pollutants concentrations. A comparison with the correspondent stationary approach based on National Census data, allows detecting the inability of latter in estimating the actual variability of population exposure. Significant underestimations of the amount of population exposed to daily PM2.5 WHO guideline was identified for the Census approach. Very small differences (up to a few μg/m3) on exposure were detected for gender and age ranges population classes. © 2016 Elsevier Ltd.


Franci D.,ARPA Lazio | Aureli T.,ARPA Lazio
Radiation Protection Dosimetry | Year: 2014

The indoor radon concentration was measured in 16 schools and 6 public departments in the Ardea municipality, using both active and passive detectors. The annual concentration of radon has been determined as the mean of two consecutive 6-month periods of sampling from January 2012 to January 2013. The indoor radon level measured in the monitored buildings ranged from 17 to 918 Bq·m. -3, with a mean value of 154 Bq·m. -3. In addition, the correlation between short-term and long-term measurements was studied. Experimental data demonstrate that the deviation of short-term measurements with respect to polyallyl diglycol carbonate data does not exceed ±40 % in a very extended range of radon concentrations. © The Author 2014. Published by Oxford University Press. All rights reserved.


Trevisi R.,Research Sector | Cardellini F.,ENEA | Leonardi F.,Research Sector | Vargas Trassierra C.,University of Cassino and Southern Lazio | Franci D.,ARPA Lazio
Radiation Protection Dosimetry | Year: 2014

The inhalation of short-lived radon decay products (RDP) yields the greatest contribution to the natural radiation exposure. This paper deals with a study carried out to improve the knowledge of the behaviour of RDPs, their interaction with particulates and the plateout during the time. The tests confirmed that a high aerosol particle concentration increases the probability that an ion sticks to aerosol and remains long in the air, leading to both an increase of F and a decrease of fp, as reported in the literature. The same experimental protocol applied in a small radon chamber showed a strong reduction of the equilibrium factor (an average of -10 %), because in a small environment the plateout phenomenon prevails on the attachment to particulate. © The Author 2014.


PubMed | ENEA and ARPA Lazio
Type: Journal Article | Journal: Radiation protection dosimetry | Year: 2015

Time-integrated measurements of indoor radon levels are commonly carried out using solid-state nuclear track detectors (SSNTDs), due to the numerous advantages offered by this radiation detection technique. However, the use of SSNTD also presents some problems that may affect the accuracy of the results. The effect of overlapping tracks often results in the underestimation of the detected track density, which leads to the reduction of the counting efficiency for increasing radon exposure. This article aims to address the effect of overlapping tracks by proposing an alternative calibration technique based on the measurement of the fraction of the detector surface covered by alpha tracks. The method has been tested against a set of Monte Carlo data and then applied to a set of experimental data collected at the radon chamber of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti, at the ENEA centre in Casaccia, using CR-39 detectors. It has been proved that the method allows to extend the detectable range of radon exposure far beyond the intrinsic limit imposed by the standard calibration based on the track density.


PubMed | ENEA and ARPA Lazio
Type: Journal Article | Journal: Radiation protection dosimetry | Year: 2016

The aim of this study was to investigate the effect of ageing and fading on PADC detector response, as a function of the storage time and temperature. Several groups of CR-39 detectors provided by Radosys, Ltd. were exposed at the reference radon chamber of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti, at the ENEA centre in Casaccia. The results indicate that low-temperature storage inhibits the effect of both ageing and fading. Finally, the overall reduction in CR-39 sensitivity due to the combined ageing/fading effect was estimated. In particular, the sensitivity of the detectors continuously exposed in air at room temperature over 6 and 3 months was reduced, respectively, by 7.5 and 4 %.


PubMed | ARPA Lazio
Type: Journal Article | Journal: Radiation protection dosimetry | Year: 2014

The indoor radon concentration was measured in 16 schools and 6 public departments in the Ardea municipality, using both active and passive detectors. The annual concentration of radon has been determined as the mean of two consecutive 6-month periods of sampling from January 2012 to January 2013. The indoor radon level measured in the monitored buildings ranged from 17 to 918 Bqm(-3), with a mean value of 154 Bqm(-3). In addition, the correlation between short-term and long-term measurements was studied. Experimental data demonstrate that the deviation of short-term measurements with respect to polyallyl diglycol carbonate data does not exceed 40 % in a very extended range of radon concentrations.

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