Which gas is NOT listed as a potential toxic gas at a WWTP?

• A. Hydrogen Sulfide
• B. Methane
• C. Carbon Monoxide
• D. Neon Tetroxide

Answer: (D)

Gas hazards at a wastewater plant include hydrogen sulfide, methane, and carbon monoxide. Hydrogen sulfide is highly toxic even at low concentrations, with rapid onset of dizziness, loss of consciousness, and can be fatal in occupational exposures. Methane isn’t toxic in the conventional sense, but it can displace oxygen and create an explosive atmosphere in confined spaces, making it a major safety concern. Carbon monoxide is toxic because it binds tightly to hemoglobin, reducing the blood’s ability to carry oxygen. Neon tetroxide isn’t a recognized or real hazard at WWTPs; neon gas is inert and a “neon tetroxide” compound doesn’t appear in standard lists of plant hazards.