Lately I have been having quite a few service calls that revolve around sewer gas smells and of course the customer asks a logical question ''is sewer gas bad for you?''. Well, the only way to answer that question is with one word- depends. See, there is no such thing as sewer gas. By that I mean there is no actual chemical called sewer gas. Sewer gas is just what the name implies, its gas that comes from the sewer. What the composition of that gas is, varies. It varies from day to day and from locality to locality. It could be totally benign one day and immediately toxic the next day. See why there is no good answer to that question other than ''depends''. Common sense must steer your course. This link is an article on the subject from Standard Sanitary Manufacturing in 1912. They didn't put as much emphasis on the deadly aspect of it as this link to a State of Wisconsin article does. You'll have to judge for yourself on this one. My personal feeling is it can't be any good for you.