A confined space is a place which is substantially enclosed (though not always entirely), and where serious injury can occur from hazardous substances or conditions within the space or nearby (e.g. lack of oxygen).
The Management of Health and Safety at Work Regulations 1999, as they apply to work in confined spaces, require employers to identify the hazards present, assess the risks and determine what precautions to take.
The Confined Spaces Regulations 1997 apply where assessment identifies risks of serious injury from work in confined spaces.
The Confined Spaces Regulations 1997