Sewer gas Sewer gas Sewer gas is a complex mixture of toxic and nontoxic gases produced and collected in sewage systems by the decomposition of organic household or industrial wastes, typical components of sewage. Sewer gases may include hydrogen sulfide, ammonia, methane, esters, carbon monoxide, sulfur dioxide and nitrogen oxides. Improper disposal of petroleum products such as gasoline and mineral spirits contribute to sewer gas hazards. Sewer gases are of concern due to their odor, health effects, and potential for creating fire or explosions. Sewer gas is typically restricted from entering buildings through plumbing traps that create a water seal at potential
Damp (structural) indoor spaces. Moisture sources, such as hot tubs or indoor swimming pools, should be covered by airtight lids when not in use, thus humidity levels stay low in the indoor environment. Condensation comes from water vapour within the building. Common sources may include cooking, bathing, dishwashers, etc. The moisture in the air condenses on cold surfaces, sometimes inside the walls called interstitial condensation. Buildings with poorly insulated walls are very prone to this problem. It often causes damage similar to damp in a building and often appears in similar places. This is because it occurs in the "dead air" pockets