Determination of the minimum measurement time for estimating long-term mean radon concentration

Active Monitoring of Residential Radon in Rome: A Pilot Study

We present an overview of the potential of active monitoring techniques to investigate the many factors affecting the concentration of radon in houses. We conducted two experiments measuring radon concentration in 25 apartments in Rome and suburban areas for two weeks and in three apartments in the historic center for several months. The reference levels of 300 and 100 Bq/m³ are overcome in 17% and 60% of the cases, respectively, and these percentages rise to 20% and 76% for average overnight radon (more relevant for residents' exposure). Active detectors allowed us to identify seasonal radon fluctuations, dependent on indoor-to-outdoor temperature, and how radon travels from the ground to upper floors. High levels of radon are not limited to the lowest floors when the use of heating and ventilation produces massive convection of air. Lifestyle habits also reflect in the different values of gas concentration measured on different floors of the same building or in distinct rooms of the same apartment, which cannot be ascribed to the characteristics of the premises. However, the finding that high residential radon levels tend to concentrate in the historic center proves the influence of factors such as building age, construction materials, and geogenic radon.

Effect of sampling duration on the estimate of pollutant concentration behind a heavy-duty vehicle: A large-eddy simulation

Plume chasing is cost-effective, measuring individual, on-road vehicular emissions. Whereas, wake-flow-generated turbulence results in intermittent, rapid pollutant dilution and substantial fluctuating concentrations right behind the vehicle being chased. The sampling duration is therefore one of the important factors for acquiring representative (average) concentrations, which, however, has been seldom addressed. This paper, which is based on the detailed spatio-temporal dispersion data after a heavy-duty truck calculated by large-eddy simulation (LES), examines how sampling duration affects the uncertainty of the measured concentrations in plume chasing. The tailpipe dispersion is largely driven by the jet-like flows through the vehicle underbody with approximate Gaussian concentration distribution for x ≤ 0.6h, where x is the distance after the vehicle and h the characteristic vehicle size. Thereafter for x ≥ 0.6h, the major recirculation plays an important role in near-wake pollutant transport whose concentrations are highly fluctuating and positively shewed. Plume chasing for a longer sampling duration is more favourable but is logistically impractical in busy traffic. Sampling duration, also known as averaging time in the statistical analysis, thus has a crucial role in sampling accuracy. With a longer sampling (averaging) duration, the sample mean concentration converges to the population mean, improving the sample reliability. However, this effect is less pronounced in long sampling duration. The sampling accuracy is also influenced by the locations of sampling points. For the region x > 0.6h, the sampling accuracy is degraded to a large extent. As a result, acceptable sample mean is hardly achievable. Finally, frequency analysis unveils the mechanism leading to the variance in concentration measurements which is attributed to sampling duration. Those data with frequency higher than the sampling frequency are filtered out by moving average in the statistical analyses.

Radon Research in Poland: A Review

The article presents the most important results of radon research in Poland. Large-scale research, launched in this country in the early 1950s, was originally linked to using radon dissolved in groundwater in balneotherapy as well as to uranium ore exploration and mining. This early research focused on the area of the Sudetes and nowadays it is also south-western Poland where most radon research is being conducted. This is chiefly due to the geological structure of the Sudetes and the Fore-Sudetic block, which is propitious to radon accumulation in many environments. Radon research in Poland has been developing dynamically since the 1990s. A lot of research teams and centres have been formed, all of them using a variety of methods and advanced measurement equipment enabling research into radon occurrence in all geospheres and all spheres of human activity. The author presents the contribution of Polish science to broadening human knowledge of the geochemistry of radon, particularly of 222Rn isotope. The article also presents the ranges and mean values of 222Rn activity concentration measured in different environments in Poland including the atmospheric air, the air in buildings and underground hard-coal and copper mines, the cave air, the air in underground tourist sites and abandoned uranium mines, as well as soil air and groundwater.

Long- and short-term indoor radon survey in the Ardea municipality, south Rome

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.