What is the safe concentration range of oxygen in a confined space?

The safe concentration range of oxygen in a confined space is crucial for ensuring the health and safety of workers. The correct range is between 19.5% and 23.5% oxygen. This range is established by OSHA standards because it is the optimal oxygen level for human respiration and cognitive function.

At concentrations below 19.5%, oxygen levels can become insufficient for safe breathing, leading to hypoxia, which can impair judgment and physical ability, and increase the risk of unconsciousness or other health complications. Conversely, concentrations above 23.5% can pose a serious fire and explosion risk, as higher oxygen levels can significantly increase the flammability of materials and create dangerous conditions in a confined space.

Therefore, maintaining oxygen levels within the range of 19.5% to 23.5% is essential for worker safety in confined environments, making this the correct answer.