Unit 4- Confined Space

Confined Space

The scenario described can best be described as a “hazardous atmosphere” in the classification of confined spaces. A hazardous atmosphere is one that can predispose employees to the risk of incapacitation, death or prevent one’s ability to self-secure themselves. More specifically, Appendix A of 29 CFR 1910.146 identifies a hazardous atmosphere as one that contains flammable gas, moist or vapor that exceeds 10% of the gas’ lower flammable limits and an oxygen concentration of either less than 19.5% or more than 23.5% (Leao, Santos, Mello & Morais, 2015). The hazardous atmospheres of confined spaces may also consist of combustible dust whose concentration exceeds their respective lower combustible limits. Moreover, such atmospheres of confined spaces also include any substance that could pose a potential danger to employees working in such spaces (Burlet-Vienney, Chinniah, Bahloul & Roberge, 2015).

In the case scenario, the oxygen level was at 16% when the pit was opened. After ventilation, the oxygen level rose to 18% and remained constant after that. This oxygen level is below 19.5% and hence falls under the definition of a hazardous atmosphere. Secondly, the pit is 12 feet deep; employees working at the bottom of the pit may not manage to get to safety if any occurrence that threatens their life or health. The content of the leaking waste material has also not been tested. It could potentially be a health hazard for the employees. Therefore, this pit fits the definition of a hazardous atmosphere under the classification of confined spaces. 

Standard Operating Procedure

SOPConfined Space Entry
Revision number1
Last Reviewed DateDecember 3, 2018
SOP OwnerPlant Engineer
Implementation DateDecember 3, 2018


The Purpose of this SOP is to document sets to be undertaken when accessing confined spaces classified as a hazardous atmosphere. It highlights the responsibility for authorizations and requirements of such authorization when accessing such confined spaces.


This SOP covers any employee, contractor or other external parties that may want to access the controlled space classified as a hazardous atmosphere.


The Plant Engineer

The plant engineer is the overall person in charge of implementing this standard operating procedure. He or she shall:

  1. Ensure that all hazardous atmosphere confined spaces are identified classified and documented.
  2. Conduct training for all personals expected to work under such confined spaces.
  3. Coordinate with corresponds from outside.
  4. Enforce the application of this SOP

The Entry Supervisor

The Entry supervisor shall:

  1. Shall determine when conditions for entry outlined under this procedure are suitable for entry is met before people are allowed to enter.
  2. Authorize entry.
  3. Put in place measures to deter unauthorized personnel from entering.
  4. Constitute and avail a rescue team during the time of entry. 


  1. Evaluate the confined space before entry to determine any potential hazard. It includes the evaluation of the physical hazards, air quality, and oxygen levels
  2. Open up more space to allow more oxygen into the confined space.
  3. Reevaluate the oxygen level to ensure that it is between 19.5 and 23.5 before entering the confined space.
  4. Ensure that ladders and other entry equipment are provided for before one can access the confined space.
  5. Ensure that a rescue team is constituted and available at the time of entry.
  6. Obtain the confined space work permit before accessing the confined space
  7. Put on the right personal protective equipment before accessing the confined space.
  8. Access the confined space using appropriate equipment such as ladders and ensure that such ladders remain in place during the time of entry to enable the people who enter easily exit if they detect any danger.
  9. Be conscious of the environment when working under such confined space and get out immediately you sense dangerous conditions.


Leao, D., Santos, M., Mello, M., & Morais, S. (2015). Consideration of occupational risks in construction confined spaces in a brewery. Occupational Safety and Hygiene III, 343-347. 

Burlet-Vienney, D., Chinniah, Y., Bahloul, A., & Roberge, B. (2015). Occupational safety during interventions in confined spaces. Safety Science, 79, 19-28.