What action is important to control oxygen levels in a confined space?

Air testing is crucial for controlling oxygen levels in a confined space because it directly measures the concentration of oxygen and other gases present in the environment. Before entering a confined space, it is essential to ensure that the oxygen level is within a safe range—typically between 19.5% and 23.5%. By conducting air testing, workers can identify whether oxygen levels are deficient, enriched, or within a normal range, and take necessary actions based on the results.

Proper air testing helps ensure the safety of personnel by allowing them to assess the conditions they will face inside the space. Regular monitoring may also be required to detect any changes in gas concentration over time, ensuring that the environment remains safe while work is being performed.

The other actions listed may contribute to the overall safety and effectiveness of operations in confined spaces, but they do not specifically address the need for immediate assessment of oxygen levels in the way that air testing does.