In typical modern livestock housing, where animals are densely confined, dusts and gases commonly reach harmful concentrations. The sources of these harmful dusts and gases include the animals, their feed, and their feces. Ammonia comes primarily from the animals' urine and feces, and hydrogen sulfide from manure pits. Hydrogen sulfide can rise to harmful levels, especially during agitation and emptying. Dust and gas levels are highest in winter, although dust levels increase whenever animals are fed, handled, or moved. This article reviewed the respiratory health effects of these dusts and gases on workers in swine buildings. Similar respiratory responses do occur among poultry confinement workers and can occur (although less commonly and severely) among workers in other types of confinement operations, such as beef cattle, dairy cattle, or sheep. Confinement dusts and gases can affect any exposed person within a short time and in extreme cases have caused sudden death or have forced owners, employees, and veterinarians to stay out of confinement buildings or seek other employment. Responses vary from person to person, may affect any part of the respiratory tract, and may include inflammatory, toxic, or allergic processes. The dust exposures cause health effects similar to other agricultural dust exposures. Health effects include acute or chronic bronchitis (the most common reaction), increased airways reactivity (occupational asthma), a systemic influenza-like reaction, thermal ODTS, a general mucus membrane irritation syndrome, and chronic sinusitis. When manure pits constructed underneath confinement buildings are agitated in the process of emptying, the concentration of hydrogen sulfide can rise to lethal levels within seconds; this has caused a number of deaths. Research suggests that chronic obstructive pulmonary disease may occur among confinement workers with long-term exposure, although that has not yet been clearly shown. When diagnosing and treating respiratory illness in confinement workers, physicians should make a conscientious attempt to discover links between exposure to dusts and gases in the houses and the illness. This will avoid the overuse of symptomatic treatment that is ineffective in the long run. Instead, a patient must be protected by reducing dust and gas levels in the confinement house through management practices and engineering, or by use of respirators. Preemployment considerations should include a screening and warning to smokers and to persons with a history of concurrent respiratory or cardiac conditions, since they tend to have more frequent and more severe problems. Confinement house workers should be monitored for development of respiratory disease. Manure pits should never be entered without proper respiratory protection, and when pits are being agitated or emptied, workers should stay out of the buildings above them.
