Working in confined spaces presents significant health and safety challenges, which require stringent guidelines and measures to ensure the well-being of workers. The document titled "Working in Confined Spaces", published by the Electricity Industry Occupational Health Advisory Group (OHAG) in England, provides detailed advice and guidance to meet the requirements of the Confined Spaces Regulations 1997. This article aims to summarize the key aspects of this document for occupational health nurses and doctors.


Each year, a number of people are killed or seriously injured in confined spaces, including not only those working within these spaces but also those attempting rescues without proper training and equipment. The primary aim of this document is to provide essential advice and guidance to comply with the Confined Spaces Regulations 1997. While avoiding work in confined spaces is ideal, when unavoidable, it is crucial to identify hazards, assess risks, and determine necessary precautions to protect individuals.

Aims of the Document

The document aims to:

  1. Identify relevant existing legislation and guidance.
  2. Highlight key health hazards associated with confined spaces.
  3. Summarize measures required to address these risks.
  4. Describe a process for medical assessment for individuals performing this safety-critical activity.

Relevant Legislation

Several pieces of legislation are pertinent to working in confined spaces:

  • The Confined Spaces Regulations 1997
  • The Management of Health and Safety at Work Regulations 1999
  • The Control of Substances Hazardous to Health Regulations 2002 (as amended)
  • The Personal Protective Equipment at Work Regulations 1992 (as amended)
  • The Provision and Use of Work Equipment Regulations 1998
  • Electricity at Work Regulations 1989
  • Workplace (Health, Safety & Welfare) Regulations 1992

Relevant Guidance

Key guidance documents include:

  • "Safe Work in Confined Spaces" (L101) – Confined Spaces Regulations 1997, Approved Code of Practice, Regulations, and Guidance.
  • "Guidance on Permit to Work Systems" (HSG250) – for the Petroleum, Chemical, and Allied Industries.
  • "Steps of Risk Assessment" (INDG163(REV2)).

Definition of Confined Space

A confined space is any enclosed area where there is a risk of death or serious injury from hazardous substances or dangerous conditions, such as a lack of oxygen. Examples include:

  • Storage tanks
  • Silos
  • Sewers
  • Trenches
  • Ductwork
  • Unventilated or poorly ventilated rooms
  • Combustion chambers in furnaces

Principal Hazards

Working in confined spaces poses various dangers, such as:

  • Lack of Oxygen: Can result from reactions between soils and the atmosphere, rust formation in steel tanks, or carbon dioxide displacement by groundwater.
  • Poisonous Gases, Fumes, or Vapors: Can accumulate in sewers, manholes, and tanks, or arise from residues in vessels.
  • Hot Conditions: Can lead to dangerous increases in body temperature.

Risk Assessment

A competent person must conduct a suitable and sufficient risk assessment before any work in a confined space. The assessment should consider:

  • The task
  • The working environment
  • Working materials and tools
  • The suitability of individuals for the task
  • Emergency rescue arrangements

Confined Spaces Regulations

Employers' duties under these regulations include:

  • Avoiding entry into confined spaces when possible.
  • Implementing safe systems of work.
  • Ensuring rescuers' capabilities and establishing emergency procedures.

Safe Systems of Work

When entry into a confined space is unavoidable, a safe system of work must be established. Key elements include:

  • Appointment of a supervisor
  • Assessing employee suitability
  • Isolation of the space
  • Cleaning before entry
  • Ensuring proper ventilation
  • Testing the air quality
  • Providing appropriate tools, lighting, and breathing apparatus
  • Preparing emergency arrangements
  • Establishing communication and permit-to-work systems

Emergency Procedures

Effective emergency procedures are essential and should be based on the specific risks of the confined space. These procedures include:

  • Communication systems
  • Rescue and resuscitation plans
  • Ensuring rescuers' capability
  • First aid procedures
  • Coordination with local emergency services

Health Assessment

Employers must ensure that individuals working in confined spaces undergo health assessments prior to commencing work and at regular intervals thereafter. These assessments should be conducted by experienced occupational health professionals and tailored to the specific task requirements and hazards. Assessments may include:

  • Health-based questionnaires
  • Baseline clinical examinations (e.g., height, weight, pulse, blood pressure)
  • Visual acuity and audiometry tests
  • Lung function and physical fitness testing
  • Evaluation of suitability to use breathing apparatus


Working in confined spaces requires stringent safety measures and health assessments to protect workers from significant hazards. The document "Working in Confined Spaces" by the Electricity Industry Occupational Health Advisory Group provides essential guidelines for occupational health professionals to ensure the safety and well-being of workers.

While there are many international standards for working in confined spaces, the guidelines provided by the Electricity Industry Occupational Health Advisory Group are widely recognized and used in England.

For more information about this standard document or guidelines, please visit: Energy Networks Association