radon

In order to demonstrate conformity with the current Building Regulations, many house builders are incorporating sumps beneath the ground floor construction of houses within the designated Radon Affected Areas. These sumps will allow for later depressurisation of the below ground floor construction and thereby prevent radon passage to the internal building environment. There are concerns regarding the costs of these measures and also the potential for these sumps to be used by vermin as nesting sites as well as their effectiveness.

In certain parts of the United Kingdom where radon gas seeps from the ground into the basement of domestic housing, normal methods of removing this gas by using under floor extract ventilation is not appropriate. In this situation the radon gas enters the basement through the side walls of the cellar and hence into the house. Using mechanical ventilation to either pressurise or de-pressurise the cellar may be an appropriate solution to this problem, however before installing such a system in a house a ventilation strategy must be established.

Mechanical ventilation of the underfloor space is one of the most effective ways of reducing radon levels in buildings with suspended timber floors. There is a question however whether this ventilation should be supply or extract, sometimes extract is more effective, soinetiines supply is inore effective. This report presents a simple analysis of the problem and suggests the hypothesis that the relative effectiveness of supply or extract ventilation to the underfloor space depends on the relative airtightness of the floor and the soil or oversite surface.

The aim of this study was to unravel the occupational exposure to radon among underground workers. The possibility for radon mitigation by improving ventilation or by sealing was also investigated. 65 workrooms in 19 workplaces has been investigated in the ground floor, in basements and in underground spaces in southern Finland and in middle Finland. Radon concentration varied from 15 to 1636 Bq/m³du ring working hours resulting in annual dose of 0.09 to 10.3 mSv.

Some radon mitigation systems draw air with a high radon concentration from under the basement floors of houses and exhaust it outdoors. The objective of this project was to measure the reentry rates of radon released at roof level and at ground level near a house to determine whether exhaust above the roof is necessary. This was done by using a portable mockup of a radon mitigation system exhaust, with sulfur hexafluoride (SF6) as a tracer gas.

This Handbook is in three parts: Introductory, health & economics and building. The author's perspective of environmental and health issues developed during ten years as a Principal Scientist at the Building Research Establishment, including four as Head of Building Pathology. Each Section in the Handbook addresses a particular topic and many may be read independently. With this structure, it is inevitable that there is some duplication of basic information, especially in Part 2. It is intended to publish replacement and new Sections in the next few years.

Indoor radon concentrations, radon emanation rates from building surfaces, radioactivity contents of building materials and the indoor gamma dose rates for Hong Kong are all in general higher than values obtained elsewhere. An interesting phenomenon has been noted that the values of indoor radon concentrations and radon emanation rates from building surfaces in Hong Kong tend to decrease with the age of the buildings, while the absorbed gamma dose rate remains about the same.