This report gives guidance for reducing the presence of radon in new dwellings, and hence reducing the risk to occupants of exposure to radon. Interim guidance was first issued by the Department of the Environment in June 19881. Since that time much experience has been gained of its application in practice. This report has been prepared to build on the experience gained and to provide a more comprehensive explanation of the principles involved. It provides practical details on methods of protecting new dwellings

This report is one of a series giving practical advice on methods of reducing radon levels in existing dwellings. It is intended for the guidance of householders and builders who seek to reduce radon levels in dwellings by sealing cracks and other discontinuities in solid ground floors. The remedial measures described are mainly for concrete floors laid directly on the ground but some of the principles could be used with suspended concrete floors and, to a lesser extent, with floors consisting of large stone slabs.

Radon is an inert radioactive gas released into the atmosphere from certain minerals and man-made products in which it is produced. It can accumulate in confined spaces. Radon emanation into a building can come from: the underlying soil, the building materials, tap water and natural gas. The principal isotope, 222Rn, decays to products which if inhaled can result in exposure of the respiratory tract to alpha radiation. The decay products, radon daughters, are significant because of their potential to cause health effects.

Active sub-slab depressurization (SSD) systems are an effective means of reducing indoor radon concentrations in residential buildings. However, energy is required to operate the system fan and to heat or cool the resulting increased building ventilation. We present  regional and national estimates of the energy requirements, operating expenses and C0₂ emissions associated with using SSD systems at saturation (i.e. in all US homes with radon concentrations above the EPA remediation guideline and either basement or slab-on-grade construction) .

During the period August 1993-0ctober 1994 a study was undertaken throughout British Telecommunications pie to assess occupational exposure to radon. This paper is concerned only with that portion of the work concerned with underground structures. The results show that radon can build up to very high concentrations in manholes and implies a significant risk to those who need to work in them.

An effective way of reducing the level of radon in dwellings is to extract air from beneath the ground floor. This is usually achieved by mechanical ventilation or by the use of a radon sump. However, in some circumstances, these remedial measures may lower the air pressure inside the dwelling. In a small number of cases, this causes combustion gases from open-flued combustion appliances, such as open fires, to spill into the living spaces. Spillage of this type is potentially hazardous, and should always be avoided.

Noise from fan-assisted radon sump systems can be a problem in the home. This leaflet describes how to design a sump system with a view to minimising noise disturbance. It also includes advice on reducing noise from unsatisfactory existing systems. The leaflet will be of interest to householders, builders and designers dealing with noise from fan-assisted radon sump systems