Mechanism of death:
(1) low oxygen tension in the air (due to consumption by bacteria)
(2) methane and other flammable/explosive gases
(3) other toxic gases (hydrogen sulfide, carbon dioxide, ammonia)
Preventive steps:
(1) Post hazard signs at all openings to all manure pits.
(2) Fit all openings to manure pits with substantial metal grill covers to prevent falls or other accidental entries.
If entering the pit:
(1) Provide powered, continuous, fresh-air ventilation with explosion-proof equipment before entering a manure pit.
(2) Always test the atmosphere inside a manure pit before entering to ensure that the concentration of oxygen is adequate and that a toxic or explosive atmosphere does not exist.
(3) If there is any question about the atmosphere in the pit, proper respiratory protection (a positive-pressure, self-contained breathing apparatus) should be worn.
(4) Always wear a harness or safety belt with a lifeline secured outside the manure pit to a winch, hoist or pulley.
(5) Always make sure that someone is outside the pit who can lift the entering person from the pit in the case of an emergency.
If trying to rescue a person in the pit:
(1) Do not enter without proper respiratory protection (a positive-pressure, self-contained breathing apparatus).
(2) Call the fire department of rescue squad.
