Implication of Particle Sources in the Calculation of the Dose Arising from Exposure to Radon Progeny in Indoor Atmospheres

Abstract

Radon is ubiquitous in the biosphere and present in soils and building materials. It accounts for about half of our total irradiation dose from natural sources. An association has been demonstrated in uranium miners between their exposure to radon and its decay products and an excess risk of lung cancer, however, any effect of domestic radon exposure in the production of lung cancer remains unclear. Epidemiologic and dosimetric approaches have been used to study the problem, but there is considerable variation between the results from each method. To better estimate the risk a European large-scale research programme has been conducted. One aim of the study was to better characterise the size distribution of particulates carrying radon progeny including their variation with time and ambient conditions. A methodology was developed to measure the particulate size distribution, unattached fraction and the equilibrium factor of 222Rn short-lived daughters. Measurements were made in a traditional dwelling built on a granitic soil in Brittany. Over 11 months, radon activity concentration was on average 1,420 Bq·m–3 (240–2,800 Bq·m–3), but it was concluded that such an approach only allows assessment of the dose as the sum of the unattached and attached forms.