Basic Wastewater Operator Practice Exam

What gas is a concern in confined spaces due to its toxic nature?

1. Carbon dioxide

2. Ammonia

3. Methane

4. Hydrogen sulfide

The correct answer is: Hydrogen sulfide

Hydrogen sulfide is a significant concern in confined spaces due to its highly toxic properties. This colorless gas, often characterized by its distinct "rotten egg" smell, can be extremely dangerous even in low concentrations. Hydrogen sulfide can cause severe respiratory distress, unconsciousness, and even death if inhaled in sufficient quantities. In environments such as wastewater treatment facilities, where organic matter decomposition occurs, hydrogen sulfide is a common byproduct, making monitoring for this gas essential to ensure worker safety. Because of its toxicity and the rapidity with which it can exert harmful effects, appropriate ventilation and detection systems are critical in confined spaces to prevent exposure.