Abstract
The problem of high radon levels in homes was recognised very early in Sweden. The first measurements were made in the 1950s and recommendations on reduction measures were published in 1982, before most countries had noticed the existence of radon. The rest of the world has since done a lot of catching up. but Sweden remains in the forefront of research and action on preventing high exposures, as illustrated in this book.
The Radon Book was originally written in Swedish, but it has been well translated into English and adapted for an international audience. It covers all aspects of the subject from the production of radon in the ground to the presence of radon decay products in air, with some additional information on health risks and measurement techniques. The main part of the book, however, concentrates on remedial measures for existing buildings and preventive measures for new ones. Systematic and detailed instructions are given for identifying problems, choosing solutions and applying them.
The remedial measures developed in Sweden were initially based on those used in North America, where high radon levels were at first thought to be a man-made problem caused by building houses over uranium mine tailings. No expense was spared in solving this problem until it was found that high radon levels indoors were more commonly a result of building houses over certain rock types. The realisation that radon problems were of natural origin changed attitudes dramatically.
Sweden continued the research on remedial measures, in particular on the most effective and reliable method, sub-floor depressurisation. This measure is most appropriate in houses with concrete floors, and uses a small fan to extract the radon-laden air from under the floor. This solution has since spread around the world, despite initial scepticism. It seems that in each country the building technologists start out convinced that the buildings in their country are so different from elsewhere that sub-floor depressurisation will not work, and are then surprised to find that it does.
Sweden has an additional radon problem not commonly found elsewhere: from building materials. From 1929 to 1975 a lightweight concrete was made from alum shale. This often has uranium and radium contents a hundred times higher than ordinary building materials, and such buildings can be identified with a gamma ray monitor. Most of the dose, however, comes from the radon exhaled by the concrete, and this calls for different remedial measures from those used when the radon comes from the ground. The methods developed, such as ventilation and sealing, may also be required in some other countries, such as Italy, where it has been reported that volcanic tuffs used as building materials have caused high radon levels.
Jon Miles
This book review first appeared in NRPB's Radiological Protection Bulletin and is reproduced here with the permission of the publishers.