Manufacturing Skill Standards Council (MSSC) Safety Assessment Practice Test

An employee should not enter a confined space that has an oxygen level less than ______.

1. 17 percent

2. 20 percent

3. 19.5 percent

4. 80 percent

The correct answer is: 19.5 percent

In order to maintain a safe working environment, it is critical to monitor the levels of oxygen in confined spaces. The acceptable level of oxygen for safe human respiration is typically around 19.5 percent to 23.5 percent. When oxygen levels fall below 19.5 percent, the risk of hypoxia increases, meaning that the body is not receiving enough oxygen to function properly. This can lead to serious health issues, including suffocation or unconsciousness. Therefore, the threshold of 19.5 percent serves as a safety standard to ensure that employees can breathe safely and effectively while working in confined spaces. It is essential for employers to ensure that confined spaces are tested for oxygen levels before allowing employees to enter, as lower levels can present significant dangers.