Fatal fumes lurk in manure storage facilities

Associate Editor
Signs warn farm workers about the potential presence of deadly manure gases.

As the fall harvest gears up, farmers will be running from dusk to dawn gleaning crops from the field and moving them into storage, either at the farm or local grain elevator.

It’s also an ideal time to empty manure storage systems, spreading nutrients on newly harvested fields and ideally creating more storage space for animal waste for the coming winter months. As farmers begin stirring up manure storage facilities, invisible clouds of noxious manure gases are released.

These fatal fumes are being blamed for causing the deaths of two young Wisconsin farmers over the past four weeks. Michael Biadasz, 29, of Amherst died on Aug. 15 while agitating a non-enclosed manure storage system. A month later and just 75 miles northeast of the Biadasz farm, 16-year-old Jonas Hoover allegedly stopped the tractor he was driving to check a mechanical issue inside the manure tanker he had just emptied. Both victims died of asphyxiation (suffocation) from the manure gas.

A rural Owen teen died Wednesday, Sept. 14 as a result of a farm accident in the town of Hixon.

Kevin Erb, UW Extension, said the death of Michael Biadasz, 29, of Amherst who died Aug. 15 while agitating a non-enclosed manure storage system - and most recently Jonas Hoover, 16, of Owen, who died Sept. 14 after breathing gas fumes from a manure tanker - has increased awareness related to manure gases and prompted UW Extension to hold a Manure Gas Safety Webinar.

"Following these two incidents, we heard only one gas being blamed - methane, when actually four gases (methane, ammonia, hydrogen sulfide and carbon dioxide) are generated as manure naturally breaks down and decomposes,: said Kevin Erb, UW Extension. "What we typically see in manure gas deaths is that hydrogen sulfide is the culprit. In high enough concentrations hydrogen sulfide is instantly fatal."

Lack of oxygen

Many of the livestock farms in the U.S. use manure pits or tanks to store raw manure. Inside the pit the manure undergoes anaerobic digestive degradation,200 kinds of gases including methan, hydrogen sulfide, carbon dioxide and ammonia, said Becky Larson, UW Madison/Extension Bio-waste specialist.

“The accumulation of these gases within the confined space of the manure pit can produce an oxygen-deficient and toxic environment quickly,” Larson said.

Since most of these gases in particular hydrogen sulfide are heavier-than-air, they tend to settle in low areas of manure storage or accumulation. This is particularly dangerous for small children who should be kept away from the area. Ammonia, which is lighter than air, is often found above and around manure storage areas, according to the National Farm Medicine Center.

Gas concentrations can increase significantly at the time of agitation, Larson said.

A tractors powers equipment that helps to agitate and mix manure in this outdoor pit.

“One of the problems with agitation is that it releases gases that are produced during storage. Most times these gases will disperse quickly into the atmosphere,” Larson said. “But sometimes conditions limit that from happening, like when it’s still and there’s no wind.”

Portage County Coroner Scott Rifleman said the deaths of Biadasz and more than a dozen beef cattle near the open air football-field sized pit were caused by accidental acute exposure to hydrogen sulfide gas.

Biadasz was using a piece of farm equipment to agitate a large outdoor manure pit, which opened a crust layer on top of the pit, expelling the hydrogen sulfide gas. Despite being outside, pressure in the atmosphere trapped the poisonous fumes near the ground, preventing the gas from dissipating Rifleman said in a news release. Biadasz was found on the ground near a manure pit.

Michael Biadasz died after being overcome by toxic manure gas while agitating an outdoor manure pit on his Amherst farm.

It’s hard to predict at what distance away from the manure pit there is no risk so monitoring is recommended,” Larson said.

Deadly situation

Manure gases are invisible and may displace enough of the oxygen that the victim is overcome without warning. Those entering a confined space where manure is stored may be unaware of walking into a potentially deadly situation. Larson said there are a few warning signs that should not be ignored.

“At low concentrations hydrogen sulfide smells like rotten eggs, but as the concentration increases olfactory paralysis takes place and you can no longer smell it and may think maybe the gas has gone away,” Larson said. “The reality is that the gas can reach higher concentrations where the victim may lose consciousness and ultimately die. Don’t trust your nose.”

The old adage 'what you don't know can't hurt you' couldn't be further from the truth when evaluating the risk of entering a confined space. Because manure gas is invisible and at times odorless, it's nearly impossible to detect the danger without help from a monitor.

Understanding how much gas is in the manure storage pit before each entry could mean the difference between life and death. John Shutske, UW Madison/Extension Agriculture Engineering Specialist said monitors for measuring gas concentrations are a valuable risk management tool. It's important to note that respiratory equipment except for Self Contained Breathing Apparatus (SCBA) have no value in a toxic environment.

“You have to assume that all confined spaces are highly unsafe,” Shutske said.

Monitors are available to measure a single gas or multiple gases at the same time. Shutske recommends a four gas monitor ($500 and up) that detects the presence of oxygen, methane, hydrogen sulfide and carbon monoxide (for those using combustion engines indoors as well as heaters). Multi-gas monitors also need to be calibrated and tested before being used.

“While these are valuable tools, my concern is that people will become dependent on safety devices. They have limitations and can’t be a replacement for good judgment,” Shutske said. “Don’t ignore or disable alarms and if gas is present, get out of that situation.”

Human price

The consequences of entering a confined space filled with noxious fumes often comes with a heavy human price. A review of  77 livestock manure storage-related fatalities between 1975 and 2004 found that 22 percent of the deaths involved unsuccessful rescue attempts by coworkers, according to the Iowa Fatality Assessment and Control Evaluation Program Data Base.

Causes of Wisconsin farm fatalities between 1993-2009.

Cheryl Skjolaas, UW Madison/Extension Ag Safety and Health Specialist said two such cases in 1989 in which seven people died from asphyxiation involving entry into  manure pits was the impetus behind NIOSH issuing an alert in 1990 in effort to prevent similar tragedies.

One of the incidents occurred at a Menomonee, MI, farm just over the Wisconsin border, where five family members died in a manure pit. According to reports, the family was using a pump to empty a partially covered, 12-foot deep concrete pit and were almost finished when the drainage pump clogged.

After the first person went down inside the pit, the others followed, one by one in an attempt to save the rest. The county medical examiner later reported that it took about 90 seconds for each of the men to collapse and suffocate from the invisible cloud of gas.

"Hydrogen sulfide acts quickly on the respiratory and central nervous systems. At a high enough level just one breath of the gas can be enough," Skjolaas said. "In the last 14 months there have been four deaths from manure gas including a father and son from Bloomer, WI."

According to the Chippewa County Sheriffs Department, the father entered the manure pit by climbing down a ladder through a pipe about four feet diameter in an attempt to retrieve a wheel that broke of off a manure conveyor. When the elder man was overcome by manure gas, his son attempted to rescue him.

“It may be the most difficult thing to do when someone goes down, but please don’t dive in after them,” said Jeff Nelson, an instructor at UW Madison Biological Systems Engineering. “Without air monitoring you don’t know what you’re walking into. In many documented cases, a person tries to rescue the other and they become another victim. The best thing you can do is back out and call 911 and get more well-equipped responders on the way.”

Farm workers should always assume that any confined space used for manure storage is dangerous.

Erb says that in many cases farmers claim to have entered reception pits countless times before and nothing has happened.

Remaining vigilant

"However, there could be a difference in temperature and humidity as well as wind speed where things can very quickly and dramatically make a safe situation very unsafe," Erb said. "Part of the issue is that we're so used to working in these environments, working around manure and farm equipment that it's very easy to become complacent. The key thing is always remaining vigilant. What worked yesterday and what was safe yesterday probably isn't the same situation today."

For years Skjolaas has been trying to educate the farm community on the dangers associated with manure handling and storage.

"Sometimes I wonder if I'm missing the message. What do we need to do to best help the ag community? Do we approach designers to redesign these systems so the confined spaces have less of a risk of entry?" Skjolaas said. "How do we go that extra step and get out the information so that people take action?"