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.
Highlights
Radon (222Rn) is a naturally occurring radioactive gas generated by the decay of the naturally occurring 238U series [1,2]
Three different conditions were applied for the Range Analysis (R/S) analysis of this dwelling; namely sliding window analysis of length 8 (Figure1a) and 32 (Figure1b) and lumping analysis of length 32 (Figure1c)
This means that high present values will be followed, on the most part, by high future values while this tendency will last for numerous future timeperiods [24,25,26,27,28]
Summary
Radon (222Rn) is a naturally occurring radioactive gas generated by the decay of the naturally occurring 238U series [1,2]. Radon is directly produced by the decay of radium (226Ra) which is present in soil, rocks, building materials, underground and surface waters [1,3]. After generation it may dissolve in soil's pores and fluid. Thereafter, it migrates near or far through diffusion or convection and dilutes in atmosphere, surface and groundwater. Radon and its progeny are the most significant natural sources of radiation exposure to the general population [3] contributing to about half of the total effective dose delivered to humans from all sources of ionizing radiation. The measurement and limitation of radon concentration of buildings are important [4]
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