Too many lives have been lost during manure work. The Telling the Story Project has highlighted some of these stories, including:
- Mike’s devastating death due to hydrogen sulfide exposure while agitating manure in the open lagoon on his family’s Wisconsin operation
- Jason’s exposure to manure gas while on a tractor date with his wife, Roxy, during a busy season on their Iowa farm
- Jerry’s close call with a manure pump on his family’s dairy farm in South Dakota
Agricultural work can involve many hazards, but injuries, illnesses and death are preventable. Manure work requires particular attention to safety and health. For example, livestock manure may contain zoonotic pathogens that can spread between people and animals. Equipment used to handle or move manure can also lead to entanglement or other physical injuries. Perhaps the most common and insidious challenge is an invisible one: manure gas.
Manure gas is the most well-known agricultural hazard, especially during agitation and around storages, even open-air lagoons. Manure gas refers to several compounds formed by the natural decomposition of manure. The most concerning gases are methane (CH4), ammonia (NH3) and hydrogen sulfide (H2S). Hydrogen sulfide is especially dangerous as it can cause sudden loss of consciousness. In some situations, reduced oxygen in and around manure storages causes suffocation and even death. In other cases, manure gas exposures can cause long-term health issues.
It is important to be extra cautious around manure that contains elevated levels of sulfur, whether from gypsum bedding (calcium sulfate), poor water quality (high in sulfur) or higher-sulfur animal diets, as this will likely increase the formation of hydrogen sulfide under anaerobic situations. Higher hydrogen sulfide availability increases the risk of dangerous gas release, making the situation even more dangerous. Hydrogen sulfide gas tends to stay in liquid manure, whether the storage has a crust or not, and is then released during any manure movement or agitation. In addition, hydrogen sulfide is heavier than air, so it tends to drift along at ground level and into nearby low-lying areas, thus putting people and animals at more risk. This is different than methane and ammonia, which tend to rise up and away from manure during agitation.
A recent study from the Upper Midwest Agricultural Safety and Health (UMASH) Center surveyed 162 commercial manure applicators and found that 20% reported at least one symptom of gas exposure, like headache, dizziness, nausea or vomiting while applying manure. In addition, manure applicators said they experienced fatigue and worked long hours – an average of 18.3 hours per day during the busy season. Application timing depends on environmental conditions; there can be busy seasons or short windows of two to four weeks where conditions are appropriate for applying manure.
Even during these busy seasons, manure can be handled safely. Stay prepared for the next one by following these practices for manure gas safety.
- Stay aware of the potential hazards and effects of manure gas. Any bystanders and nonessential workers should be informed of potential dangers and kept away from spaces with the potential for high levels of manure gas. Hydrogen sulfide is heavier than air, so it will stay or flow downward and is dangerous even at low concentrations. It is released in bursts during manure movement or agitation, since it tends to remain in liquid solutions rather than off-gassing during storage.
- Limit access to manure storage areas. Fencing, locked gates and warning signs can prevent unauthorized access to storage areas. During manure agitation, prevent access to low-lying areas next to the structures. Consider a buffer zone of at least 20 feet around the structure. Bystanders and nonessential workers should stay clear during agitation and manure pump-out operations. Move animals away from manure areas before agitation or pumping. Keep children away, as even low concentrations of toxic gases can harm them.
- Ensure ventilation before and during pumping and while working nearby. When agitating manure storages below animal living areas, be aware that dangerous levels of toxic gases move up through slatted floors into animal housing. Ensure these areas are well-ventilated before and during agitation. In some cases, people and animals may need to be removed.
- Consider using a portable gas monitor or detector to help monitor the hazards relevant to your operation. These are relatively inexpensive and sound an audible alarm when dangerous levels of toxic gas are present. Refer to this Great Plains Center for Agricultural Health resource for technical guidance on selecting and using gas monitors. Be sure to take proper precautions when the system alarms.
- Do not enter areas with high levels of manure gas. If the gas monitoring system ever alarms, all workers should move away, use a self-contained escape respirator if necessary, and return only when measurements show no health risk. If someone is overcome with manure gas, whether in a confined space or outside near a manure storage, do not attempt to enter the area to help them. Call emergency responders (911) and ventilate the space as much as possible. No one should enter unless properly trained and outfitted with a self-contained breathing apparatus and a body harness attached to a retrieval system.
- Work in teams rather than alone, with at least two people present during any manure handling. There should be at least one experienced person directly involved in manure agitation or movement and at least one more person at a safe distance monitoring the activity to offer assistance.
- Plan ahead to prevent fatigue and stay prepared in an emergency.
