What is the acceptable oxygen concentration range before entering a confined space?

What is the acceptable oxygen concentration range before entering a confined space?

• A. 19.5% to 23.5%
• B. 21% to 24%
• C. 18% to 22%
• D. 20% to 25%

Answer: (A)

Oxygen levels in a confined space must stay within a narrow window: enough to breathe safely, but not so high that it increases the risk of fire. The acceptable range for entry is 19.5% to 23.5% oxygen. If oxygen drops below 19.5%, people can quickly become unconscious or suffocate. If it rises above 23.5%, the environment becomes more prone to ignition and combustion, posing a serious hazard to anyone entering or working inside. To maintain safety, workers use calibrated gas detectors and ventilation to bring and keep the space within this range, and they follow permit-required procedures for entry. The other ranges either allow too little oxygen or too much, which is why they’re not considered acceptable.

Oxygen levels in a confined space must stay within a narrow window: enough to breathe safely, but not so high that it increases the risk of fire. The acceptable range for entry is 19.5% to 23.5% oxygen.

If oxygen drops below 19.5%, people can quickly become unconscious or suffocate. If it rises above 23.5%, the environment becomes more prone to ignition and combustion, posing a serious hazard to anyone entering or working inside. To maintain safety, workers use calibrated gas detectors and ventilation to bring and keep the space within this range, and they follow permit-required procedures for entry.

The other ranges either allow too little oxygen or too much, which is why they’re not considered acceptable.