Size distribution of ambient and radioactive aerosols formed by the short-lived radon progeny

Radon and Its Short-Lived Products in Indoor Air: Present Status and Perspectives

“…Soon after lighting the candle, N increased from 5.8 mm −3 to 1600 mm −3 , and d GM decreased from 85 nm to 11 nm (Figure 9a), a similar size as that obtained recently [238]. In contrast to smoking, mostly particles smaller than 10 nm were emitted, as seen in Figure 8b (presenting the number concentrations of particles in the same size windows as in the previous section).…”

“…This was ascribed to higher 226 Ra content in carbonates (range: 12−270 Bq kg -1 , GM = 66 Bq kg -1 ) in a study showing its distribution at 70 sites in Slovenia [163]. As further explained, 238 U and 226 Ra migration by water and the high permeability of carbonate led to a wash-out of more mobile uranium and increased the 226 Ra/ 238 U ratio, for which a range of 0.8−3.2 and an arithmetic mean of two were observed. The radon emanation fraction of carbonates was also high (range: 0.010−0.55, GM = 0.18), second only to that of sea and lake sediments (range: 0.26−0.42, GM = 0.34) (Figure 3).…”

“…Radon and thoron sources are 238 U and 232 Th, respectively (Figure 1), in the ground on which a building stands, in the building material, and in used tap water and gas. Because of their half-lives and associated diffusion lengths, radon enters a building predominantly from the ground, while for thoron, its exhalation from the floor and walls in a room is generally its predominant source indoors.…”

“…In the three primordial radioactive chains, three radon isotopes are created by α-transformation of radium [1]: 222 Rn (half-life, t 1/2 = 3.82 days) in the uranium chain starting with 238 U, 220 Rn (t 1/2 = 55.6 s) in the thorium chain starting with 232 Th, and 219 Rn (t 1/2 = 3.9 s) in the actinium chain starting with 235 U (Figure 1). Only a fraction of radon atoms (emanation fraction or emanation power) succeed in leaving the mineral grain due to their recoil energy and thus enter the void space, from where they migrate through the medium either by diffusion or, more effectively and to longer distances, by being carried by gas or water [2].…”

Evaluating the impact of indoor aerosols on the performance of real-time radon sensors

“…Following decay, solid radionuclides rapidly react with vapors and trace gases to form unattached clusters in the size range 0.5-5 nm (Porstendörfer, 1994). The attachment process, influenced by aerosol sources such as cigarette smoke or cooking emissions, has been studied extensively (Porstendörfer, 1994;Vaupotic, 2011;Skubacz and Wołoszczuk, 2019), with findings indicating differing attachment rates based on aerosol size and composition (Porstendörfer, 1994). In enclosed indoor environments, surface deposition serves as the primary mechanism for reducing radon decay product concentrations, with studies indicating that higher aerosol concentrations result in reduced deposition rates (Porstendörfer, 1994).…”