In Bulgaria there is a century-long tradition of radon measurements [8]. Since 1907 with hardly any interruption radon and later also radon progeny have been measured in mineral spas, in underground mines, in the human environment and in laboratory research. Experience from all these fields was gathered in the Faculty of Physics at St. Kliment Ohridski University of Sofia. Nowadays, exposure to...

On the basis of the results of the recent combined analyses of epidemiological studies, the International Commission on Radiological Protection (ICRP) revised the lifetime excess absolute risk of radoninduced lung cancer to 5 10 per working level month (WLM). When applying this new coefficient in risk assessment, it should first be understood that the coefficient is associated with a chronic ex...

This paper reviews some aspects of solid-state nuclear track detectors (SSNTDs) and their applications in the radon and other research fields. Several geometrical models for the track growth given in the literature are described and compared. It is found that different models give close results for the dimensions of track openings. One of the main parameters that govern track formation is the b...

An account is given of the behaviour of thoron and its progeny in the indoor environment. Emphasis is placed on the spatial distribution of these radionuclides in room air and on their interactions with indoor aerosols. How these aspects of thoron and progeny behaviour give rise to special problems for measuring them and assessing their radiological impact are described. Descriptions and compar...

Continuous Air Monitors (CAMs) are used in nuclear facilities to detect airborne alpha-emitting transuranic radionuclides in work areas, stacks and ducts. We have now tested the first commercial version of the original Los Alamos/Texas A&M design for its performance. The penetration of inhalable-size particles onto the CAM filter is better than 80%, with excellent uniformity of sample. With the...

The radiation monitoring network in the Netherlands is designed to detect and track increased radiation levels, dose rate more specifically, in 10-minute intervals. The network consists of 153 monitoring stations. Washout of radon progeny by rainfall is the most important cause of natural variations in dose rate. The increase in dose rate at a given time is a function of the amount of progeny d...

Exposure to high concentrations of radon progeny (radon) produces lung cancer in both underground miners and experimentally exposed laboratory animals. To determine the risk posed by residential radon exposure, the authors performed a population-based, case-control epidemiologic study in Iowa from 1993 to 1997. Subjects were female Iowa residents who had occupied their current home for at least...

Residential radon has been found to be associated with lung cancer in epidemiological/ecological studies and the researchers have inappropriately concluded that residential radon causes lung cancer. Their conclusion relates to the linear-no-threshold (LNT) hypothesis-based, risk-assessment paradigm; however, the LNT hypothesis has been invalidated in numerous studies. It is shown in this paper ...