Hazmat diving is underwater diving in a known hazardous materials environment. The environment may be contaminated by hazardous materials, the diving medium may be inherently a hazardous material, or the environment in which the diving medium is situated may include hazardous materials with a significant risk of exposure to these materials to members of the diving team. Special precautions, equipment and procedures are associated with hazmat diving so that the risk can be reduced to an acceptable level. These are based on preventing contact of the hazardous materials with the divers and other personnel, generally by encapsulating the affected personnel in personal protective equipment (PPE) appropriate to the hazard, and by effective decontamination after contact between the PPE and the hazardous materials.[1]
There are a few well known environments, like nuclear power plant cooling systems, sewage treatment plants and sewers which require routine maintenance by divers, and which are well documented, with well-known and consistent hazards, for which standard operating procedures will have been developed, and other environments where the need for diving work is unusual and the hazards less well documented, and must be managed on a case-by-case basis, following an approved code of practice. Hazmat diving is a particular class of diving in high risk environments, normally only done by specially trained professional divers.[1]