Water Treatment Operator-in-Training (OIT) Practice Test

An operator smells hydrogen sulphide at the entrance of a deep confined space. What action should the operator take?

1. a) Proceed if the task is short, as hydrogen sulphide is only detected in low concentrations and will only cause headaches

2. b) Vent the confined space while working

3. c) Hydrogen sulphide gas in all concentrations is only an irritant, so proceed with the task

4. d) Do not enter the confined space until there is no hydrogen sulphide detected, and then only when all safety equipment is in place

The correct answer is: d) Do not enter the confined space until there is no hydrogen sulphide detected, and then only when all safety equipment is in place

When an operator detects the smell of hydrogen sulfide (H2S) at the entrance of a confined space, it is crucial to prioritize safety due to the toxic nature of this gas. Hydrogen sulfide, even at low concentrations, can pose significant health risks including irritation of the respiratory system, headaches, dizziness, and at higher concentrations, it can lead to loss of consciousness or even death. Choosing to not enter the confined space until there are no detectable levels of hydrogen sulfide is essential as it ensures that the operator is not exposing themselves to a potentially life-threatening environment. Furthermore, preparing all necessary safety equipment—such as personal protective gear and appropriate monitoring devices—helps mitigate risks associated with toxic gases. This response aligns with safety best practices, which emphasize continuous monitoring and the establishment of safe entry protocols for confined spaces. Approaching the situation differently, such as entering the space believing the concentrations are too low to cause harm or disregarding H2S as merely an irritant, significantly increases the risk of accidents and health hazards. Thus, waiting for confirmation that hydrogen sulfide levels are safe before entering not only safeguards the operator but also adheres to regulatory and industry safety standards.