Sewer gas is a mixture of gases produced and collected in sewer systems by the decomposition of organic household or industrial waste. These gases include: hydrogen, sulfide, ammonia, methane, carbon dioxide, sulfur dioxide, and nitrogen oxides. Sewer gases are of immediate concern due to their odor, health effects, and are potential for fuel explosions. Sewer gas occurs during the breakdown of waste, its present in sewers, farms, swamps, and septic tanks.
There are many symptoms of sewer gas exposures: burning eyes, nausea, migraines, trouble breathing, and dizziness. The gases are only dangerous if you are in a manhole with no air circulation. The sewer gas is extremely harmful in this situation because it’s heavier than oxygen and lingers at the bottom of manholes, sewers, and storage tanks. Do it yourselfers never climb in manholes or tanks without a personal gas monitor. Inhaling sewer gas is not risky in non- confined areas, unless it’s breathed for a lengthy amount of time.