Get safely back to business with our COVID-19 specific resources

Working Safely in Confined Spaces

Get everyone on the same paperless page.
Rated 4.6/5 stars on Capterra from 76 ratings
Available on iOS, Android and Web
Get started for FREE

What is a Confined Space?

OSHA defines a confined space across 3 criteria: (1) an area large enough to fully enter or perform certain jobs, (2) has limited or restricted means of entry or exit (e.g portals, hatches, manholes, ladders, spiral stairways, crawl spaces or long distance to exit); and (3) Not designed for continuous occupancy. Examples of confined spaces include tanks, vaults, pits, manholes, tunnels, equipment housings, pipelines, boilers, furnaces, compactors, sewers, attic spaces and elevator pits. Common work performed in confined spaces include maintenance, inspection, repair and cleaning.

A permit-required confined space also known as a “permit space” contains or has the potential to contain a hazardous atmosphere or any other serious safety or health hazards. It is characterized as a high risk workplace and requires regulatory permits and strict entry and safety procedures.

Statistics shows that an average of 90 people die each year while working in confined spaces in the United States alone. Most of these incidents are caused by asphyxiation or oxygen deficiency due to the presence of deadly gases while performing certain jobs. Detailed safety procedures must be thoroughly conducted to ensure all entrants will be provided adequate protection while performing their job inside the confined space. Moreover, employers are responsible for educating and reinforcing their workers about safety rules.

This article will help you understand the dangers of confined spaces and the how to be safe when working inside them. You can also browse our free collection of iAuditor confined space safety checklists to help streamline your inspection process and go paperless.

Confined Space Hazards

The main hazard when working in a confined space is the deadly atmosphere due to presence of carbon monoxide,hydrogen sulfide and methane gas that may result to oxygen deficiency or asphyxiation.

Outside the confined space, 21 percent oxygen necessary to sustain life. Oxygen in confined spaces tends to go low. It might be used by rusts, bacterial growth and slime. Other gas may enter the confined space and displace the oxygen. Operations like heating will consume oxygen. If oxygen is reduced to 12 to 16 percent, workers will increase pulse and respiration and experience loss of coordination. If the oxygen decreases to 6 to 10 percent, they will experience nausea, vomiting, loss of consciousness and even death.

Other common confined space hazards include unguarded machinery, exposed live wires and heat stress.

5 Safety Tips for Working in Confined Spaces

Confined spaces, particularly permit spaces must be areas only accessible by trained professionals. Here are some general safety tips to help you stay safe in confined spaces:

  1. Area must be free from hazards – Before entering a confined space, ensure that it has a permit prior to entry and the area is free from harmful materials and substances.
  2. Test the atmosphere – A trained worker must conduct a series of atmosphere tests (oxygen, hydrogen and explosive gas tests) which need to be recorded or included on the work permit.
  3. Ventilate – Never use the ventilator as a vacuum to draw the air outside. Make sure your fan is safe and grounded. Also, test the atmosphere as much as possible. If the atmosphere is within limits, it is recommended to ventilate again.
  4. Watch one another – When someone is working on a confined space, always ensure a workaround watch who can call rescue teams for emergencies or is capable and equipped to conduct a rescue.
  5. Use PPE – Use harness, lifeline or continuous gas monitoring devices. Also, use a self contained breathing apparatus if needed.


Sare Hawes

SafetyCulture staff writer