Did you know that besides methane, and all the toxic fumes found in sewer gas, there are also viruses found in those nasty fumes? Common biological agents found in sewer systems may be bacteria, viruses, or parasites. Hydrogen sulfide has been reported as the leading cause of sudden death in the workplace. At concentrations in air of approximately 300 ppm, H2S can be immediately deadly. So give your family and workplace permanent protection this winter. Drop in a Sewer Skewer!