Research Article
Dimitrios Nikolopoulos, Erm
Abstract
Radon and progeny (218Po, 214Pb, 214Bi and 214Po) are important indoor radioactive air pollutants with impact to humans. Radon is an inert gas that enters buildings from outdoor air, water and soil, especially via gaps around pipes and cables and through cracks in floors. Indoors, radon progeny remain free, or attach to indoor aerosols dust and water droplets. Hence, inhalable indoor radioactive mixtures are created which enter human lungs and irradiate tissues. The radiation exposure depends on several parameters some of which are the building characteristics, local geology, breathing rate and others. This work aimed to estimate Hurst exponents (H) of time-evolving radon signals of Greek apartment dwellings. The signals were collected with Alpha Guard Pro and include at least 24 hours of measurements in each dwelling. Hurst exponents were calculated by the R/S method through sliding on overlapping windows and lumping on nonoverlapping sequential windows. The scope was to identify whether radon dynamics are governed by persistent, antipersistent behavior or if these are uncorrelated. Most signals presented significant long-memory segments with important persistent sub- segments.