OSHA 10-Hour Construction ReviewFocus Four HazardsHard
A worker is preparing to enter a confined space, a large storage tank, for cleaning. The tank previously contained a flammable liquid and has limited ventilation. Which of the following is the MOST critical initial step before any worker enters the tank?
- AEnsure the worker has a respirator.
- BVerify a standby person is present outside the tank.
- CConfirm the worker has received confined space entry training.
- DTest the internal atmosphere for oxygen levels, flammable gases, and toxic vapors.
Show answer & explanationAnswer & explanation
Correct answer: D. Test the internal atmosphere for oxygen levels, flammable gases, and toxic vapors.
Atmospheric testing is the most critical initial step for confined space entry, especially for spaces that contained flammable liquids. It determines if the space is safe to enter or if further ventilation/purging is required, directly addressing immediate life-threatening hazards.
Why the other options are wrong
- A. While a respirator may be needed, testing the atmosphere first determines if it's necessary and what type.
- B. A standby person (attendant) is required, but ensuring atmospheric safety precedes entry.
- C. Training is essential, but it's a prerequisite to the job, not the most critical *initial step* immediately prior to entry for hazard control.
Confined Space Atmospheric Testing
Before entering a permit-required confined space, the internal atmosphere must be tested for oxygen, flammability, and toxicity.
- Identifies immediate life-threatening hazards.
- Must be performed by a qualified person.
- Continuous monitoring may be required during entry.
Memory trick: Atmosphere first, then the rest. Don't guess, just test!