Several cases of livestock and human deaths have resulted from exposure to hydrogen sulfide when pits were being pumped or when people entered a pit during pumping. Methane is also produced through anaerobic digestion of manure. There is some potential for pockets of methane to develop, but levels that could cause explosions or asphyxiation are extremely rare under normal conditions. The major source of carbon dioxide in a building is produced by animal respiration. Problems arise when ventilation or power fails and levels build over several hours as oxygen is depleted.
Carbon monoxide is produced by unvented gas heaters.
Warning signs of exposure are fatigue, headaches, possible nausea and impaired mental ability. Pregnant women working in farrowing or nursery buildings should be aware of the potential health hazard of carbon monoxide exposures to a developing fetus. In shallow pits with scrapers or pull plugs, adding a thin layer of water after scraping or draining will help keep ammonia in solution rather than in a gaseous s gutter systems with water, instead of recycled wastes, will have the same effect. Avoid air movement through manure channels from one room to another or from manure pits back into the barn. This air will carry manure gases into the room.