Council Directive 92/57/EECShow full title

Council Directive 92/57/EEC of 24 June 1992 on the implementation of minimum safety and health requirements at temporary or mobile constructions sites (eighth individual Directive within the meaning of Article 16 (1) of Directive 89/391/EEC)

6.Exposure to particular risksU.K.

6.1.Workers must not be exposed to harmful levels of noise or to harmful external influences (e.g. gases, vapours, dust).U.K.
6.2.If workers have to enter an area where the atmosphere is liable to contain a toxic or harmful substance or to have an insufficient oxygen level or to be inflammable, the confined atmosphere must be monitored and appropriate steps taken to prevent any hazards.U.K.
6.3.A worker may not in any circumstances be exposed to a high-risk confined atmosphere.U.K.

He must at least be watched at all times from outside and all appropriate precautions must be taken to ensure that he can be assisted effectively and immediately.