Asbestos Contractor/Supervisor Practice Exam

What is the correct order of testing for hazardous atmospheres in permit required confined spaces?

1. Combustible gases, toxic chemicals, oxygen deficiency

2. Oxygen deficiency, toxic chemicals, combustible gases

3. Oxygen deficiency, combustible gases or vapors, toxic chemicals

4. Toxic chemicals, oxygen deficiency, combustible gases

The correct answer is: Oxygen deficiency, combustible gases or vapors, toxic chemicals

The correct order of testing for hazardous atmospheres in permit-required confined spaces begins with assessing oxygen deficiency, followed by examining for combustible gases or vapors, and finally measuring for toxic chemicals. Starting with oxygen deficiency is crucial because oxygen levels falling below 19.5% can lead to incapacitation or death, making it the most immediate concern. Next, testing for combustible gases or vapors is essential, as explosive atmospheres could be just as dangerous, leading to an immediate threat of fire or explosion if ignited. Lastly, checking for toxic chemicals is important, but it is prioritized after assessing the more acute hazards of low oxygen and flammable atmospheres. This sequence ensures that the most life-threatening conditions are addressed first, providing a safer testing environment before assessing other hazards. Each of these steps is critical in maintaining safety for workers entering confined spaces, as they help to create an understanding of the immediate environment and prioritize actions accordingly.