Question 1001 of 234 · California Wastewater Operator Exam

Hydrogen sulfide (H2S) is especially dangerous to operators because, at higher concentrations, it

Exactly one answer is correct.

Adeadens the sense of smell, so the rotten egg odor can no longer warn the worker
Bhas no odor at any concentration, so workers cannot detect it without a meter during normal operation
Cis lighter than air and drifts away from low spots before it can be sensed
Dcauses only mild eye irritation and is dangerous only above 1,000 ppm

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Correct answer to question 1001

A: deadens the sense of smell, so the rotten egg odor can no longer warn the worker

Explanation

H2S causes olfactory fatigue, so a worker who stops smelling it may be in increasing danger. It is heavier than air and collects in low areas such as wet wells and manholes. Continuous gas monitors, not the nose, must be used.

1002Which gas is heavier than air and tends to collect in manholes and wet wells?
1003What must be done before an employee enters a permit-required confined space such as a wet well?
1004What is the minimum safe oxygen concentration in the air of a confined space before entry?
1005Which instrument reading means a confined space has a flammable atmosphere hazard?
1006Which is the purpose of a lockout/tagout procedure?
1007During lockout/tagout, who may remove a lock that was placed on a motor control center?

Hydrogen sulfide (H2S) is especially dangerous to operators because, at higher concentrations, it

Correct answer to question 1001

Explanation

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