What is this document?
INDG258 is the HSE's brief guide to working safely in confined spaces. It explains what action is necessary to meet the requirements of the Confined Spaces Regulations 1997.
Confined spaces can be deadly. People are killed every year in incidents involving confined spaces, and many more suffer serious injury. The risks include toxic atmospheres, oxygen deficiency, fire and explosion, and difficulty escaping in an emergency.
Who needs to read this?
- Employers whose workers enter confined spaces
- Self-employed people who work in confined spaces
- Managers and supervisors responsible for confined space work
- Workers who enter or work near confined spaces
- Contractors hired to carry out work in confined spaces
- Maintenance teams who may encounter confined spaces
- Anyone involved in planning or supervising confined space entry
Key points covered
The HSE guidance addresses:
- What counts as a confined space and how to identify one
- Common hazards associated with confined spaces
- Avoiding entry where possible
- Safe systems of work when entry is necessary
- Permit-to-work systems for controlling confined space entry
- Emergency and rescue procedures that must be in place
- Training and competence requirements
How this applies to you
The Confined Spaces Regulations 1997 apply to all workplaces where confined spaces are present. The regulations require employers to:
- Avoid entry to confined spaces if possible
- If entry is unavoidable, have a safe system of work
- Put emergency arrangements in place before work begins
What is a confined space?
A confined space is a place that is substantially (though not always entirely) enclosed, where serious injury can occur from hazardous substances or conditions within the space or nearby.
Examples include:
- Storage tanks, silos, and vessels
- Sewers, manholes, and drainage systems
- Pits and trenches
- Ductwork and pipework
- Unventilated or poorly ventilated rooms
- Enclosed areas where hazardous substances may accumulate
Understand the hazards
Confined space hazards include:
- Toxic atmospheres from gases, fumes, or vapours
- Oxygen deficiency which can cause unconsciousness and death
- Oxygen enrichment which increases fire and explosion risk
- Flammable atmospheres where gases or vapours may ignite
- Flooding or free-flowing solids such as grain or sand
- Excessive heat leading to collapse
- Difficulty escaping due to restricted access
Avoid entry where possible
Before entering a confined space, consider whether the work can be done another way:
- Can inspection be done remotely using cameras?
- Can cleaning be done from outside?
- Can modifications eliminate the need for entry?
Safe systems of work
If entry is necessary, you must have a safe system of work that includes:
- Competent supervision of the work
- Competent workers trained for the task and the risks
- Atmospheric testing before and during entry
- Ventilation to ensure a safe atmosphere
- Isolation of services, pipework, and equipment
- Communication systems between those inside and outside
- Rescue arrangements that do not rely on entering the space
Permit-to-work systems
For high-risk confined space work, a formal permit-to-work system ensures that:
- All safety precautions are in place before work begins
- Work is properly authorised
- Conditions are checked and recorded
- Handover between shifts is controlled
- The space is formally signed off when work is complete
Emergency procedures
Rescue arrangements must be in place before work starts. Key points:
- Never attempt rescue without proper equipment and training
- Many deaths in confined spaces are would-be rescuers
- Have suitable rescue equipment immediately available
- Ensure rescuers are trained and practised
- Know how to raise the alarm and summon emergency services
Related Safety Clarity content
- Workplace Safety Requirements - General employer duties for health and safety
Source: This page summarises HSE guidance document INDG258. For the full official guidance, visit the HSE website.