Before revision: 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.
After revision: upAn old sewer gas chimney in Stonehouse, Plymouth, England, built in the 1880s to disperse sewer gas above residentsSewer 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.