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