Symptoms of hydrogen sulfide exposure can include nausea, headaches and convulsions, according to the U.S. Centers for ...

One idea is that the gas pressure can clear a clog by pushing it down the pipes and into the sewer. A variation of this idea is that the fizz and bubbles can gradually eat away the clog.

a volume of sewer gas rushed in upon them, and before they could be helped out of the manhole at the corner of Kinzie-street three of the men were dead and two more died soon after reaching the air.