California ICC UST Inspector Practice Exam

An oxygen deficient atmosphere contains less than what percentage of oxygen by volume?

1. 23.5%

2. 21.0%

3. 19.5%

4. 17.0%

The correct answer is: 19.5%

An oxygen-deficient atmosphere is commonly defined as one where the oxygen concentration falls below 19.5% by volume. This threshold is significant because it represents the minimum level of oxygen necessary to sustain normal life for most organisms, including humans. Below this concentration, individuals may experience symptoms associated with oxygen deficiency, such as increased heart rate, shortness of breath, and impaired cognitive functions. The percentage is established based on safety standards and guidelines set by occupational health organizations, which aim to protect workers in environments where oxygen levels may decrease due to various factors such as the presence of certain gases or inadequate ventilation. Thus, recognizing that any atmosphere with less than 19.5% oxygen poses a health risk and qualifies as an oxygen-deficient environment is crucial in ensuring safety protocols are in place in potentially hazardous conditions.