Gases and odors may be a nuisance for many livestock producers, but they also can be a lifethreatening danger when confined to buildings or manure pits.
Every year in Iowa, incidents are reported in which someone is overcome by deadly manure gases. These incidents have resulted in several deaths and many more illnesses caused by exposure to poisonous gases. This does not include economic losses from animals that die from the gases.
It is difficult to know when air quality problems will occur. The best precaution is to understand the sources of air quality problems, and what to do to reduce or eliminate them. This publication will discuss five common gases found in manure storage facilities, and other hidden dangers.
Manure storage safety: How much do you know?
See answers at the end of document.
Gases are generated as animal wastes break down. Gas builds over time, often rising to the surface and escaping into the air. Enclosed livestock areas must be ventilated, even on cold winter days, to remove moisture and gases. When ventilation rates fall below a minimum, or when conditions increase the release of gas to the air (such as pit agitation), serious problems can occur.
At high concentrations, carbon dioxide and carbon monoxide can cause respiratory distress and headaches. At prolonged high exposures, these gases can be fatal. Federal standards set maximum concentrations at 5,000 parts per million (ppm), about 0.5 percent, for carbon dioxide; and 50 ppm, about 0.005 percent, for carbon monoxide.
Solution: These gases usually aren’t a problem under normal conditions with proper ventilation. However, it’s important to maintain some ventilation at all times, even when animals are not present.
Ammonia has a distinct odor, which humans can detect in concentrations as small as 5 ppm. It’s common during winter months for ammonia levels to exceed 25 ppm, even under normal winter ventilation rates. Although it is debated by safety experts, 25 ppm is frequently recommended as a maximum acceptable level for ammonia. If your eyes burn when you enter an enclosed livestock facility, you know ammonia levels are at least 20 ppm.
Solution: Provide at least a minimum winter ventilation rate throughout the year. Water attracts ammonia, so frequent rinsing of equipment or leaving at least a half-inch of water in pits or on the floor can help.
Solution: Make sure all pits and manure storage areas are adequately ventilated. Prohibit all open sparks or flames in areas near pits or storage facilities.
Within seconds of exposure, hydrogen sulfide can cause unconsciousness, which can be fatal. Concentrations as low as 1,000 ppm can result in death. The maximum allowable concentration is 10 ppm.
Hydrogen sulfide is heavier than air, so it will accumulate in underground pits or other lowlying, unventilated areas. Although its rotten egg odor can be detected at levels of less than 1 ppm, the gas will paralyze the sense of smell at higher levels.
Solution: Whenever you work in manure storage facilities, always assume hydrogen sulfide is present. Follow these safety precautions to minimize the dangers of hydrogen sulfide:
The large volume of liquid that must be stored in many manure systems is also a danger. Children and adults can drown in pits, commonly as deep as 8 feet. Pits typically have either very steep or vertical walls, making escape almost impossible.
Pits are inaccessible if they’re covered by slats, and outdoor pits with concrete lids pose few dangers to bystanders or workers. However, the cost of covering pits and the larger size of pits in recent years has lead to increasing use of open pits, both earthen and concrete. Without protection, such as high fences and locked gates, open pits are potential hazards.
Another problem may be push-off ramps used in some dairy operations. A strong safety cable at the end of the ramp may prevent a machine from falling into the pit. Beef and dairy pits also may form unstable crusts that can get covered with weeds.
Never try to rescue someone who is unconscious in a manure storage structure unless you have the proper equipment and knowledge of the situation. Multiple deaths are common because rescuers succumb to the same gases as the victim.
The immediate response should be to contact an ambulance or local emergency medical services. You may attempt a rescue if you are wearing a self-contained breathing apparatus, have a rescue line, and have another person at the end of the line to help.
Toxic odors and gases are natural by-products of all livestock operations. Persons who work in these environments must know that air quality problems can develop at any time. However, a cautious attitude and proper equipment can help you avoid a lifethreatening situation.
Manure storage safety: What can you do?
For more information
Answers to quiz: 1-a and b; 2-b; 3-True; 4-c; 5-b; 6-False
Publication #: PM 1518K
Safe Farm is an Iowa State University Extension and Outreach project helping to make Iowa farms a safer place to work and live.
For more safety information, check the web at www.abe.iastate.edu.
Disclaimer and Reproduction Information: Information in NASD does not represent NIOSH policy. Information included in NASD appears by permission of the author and/or copyright holder. More