More than nine months ago, the world changed for two Midwestern pig farming families. Four men, two pairs of fathers and their sons, were doing what they do every day - working in the barns. When something fell into the pit below, they quickly assessed the situation. With such high levels of concentration, there would no warning, no rotten egg smell for which hydrogen sulfide is known. It wouldn't take long to retrieve the tool from the pit, right? These men likely had the thought all pork producers have had at one time or another: "I'll only be down for a second. I can just hold my breath."
That assumption needs to change. Those four men died, and so have others.
Breathe at Your Own Risk
Dr. Dan Andersen, an agricultural and biosystems engineer who specializes in manure management at Iowa State University and Dr. Ren√©e Anthony with the Great Plains Center for Agricultural Health each stress the importance of taking precautions to prevent any more deaths.
On operations not pumping, concentrations of hydrogen sulfide are fairly low. Anthony explains that a concentration of 10 parts per million (ppm) is considered the safe upper limit of chronic, long-term exposure at 40 hours a week for a producer's lifetime.
"Once we start moving manure, the concentrations in the pit become airborne and can come up into the room," Anthony advised. It's at this point that hydrogen sulfide goes from relatively harmless to potentially deadly. See the chart below for the health impacts of higher levels of hydrogen sulfide.
Anthony noted there is a point at which the infamous rotten egg smell is no longer detectable. As the concentration of hydrogen sulfide increases or the longer the exposure, "olfactory fatigue" sets in.
"At high concentrations you can't smell it. You've lost the ability to smell it when it becomes really, really dangerous," she said. The Occupational Safety and Health Administration reiterates this, warning not to rely on the sense of smell to indicate presence of hydrogen sulfide or warn of life-threatening concentrations. (Read more at http://1.usa.gov/1UezRuQ)
"One One-Thousand, Two One-Thousand"
Despite the potential risks, it's still easy for pork producers to assume that risk doesn't apply to them. Especially if someone else has gone into the pit first and become incapacitated, Andersen notes that it's our natural instincts to want to help when there is distress. As Anthony explained, safety shortcuts may be taken because of two deadly thoughts:
When you think: "I can just hold my breath."
The reality: Especially for the person going into the pit to rescue someone else, it's not as simple as just holding your breath. "If you think about it, you have to try to go down, lift 150 pounds in an emotional situation with adrenaline pumping and carry that person out. You cannot hold your breath," Anthony stressed.
When you think: "I've had the fan on long enough."
The reality: Anthony points to an incident several years ago. It had been several days since the pit was pumped, it had been vented and the victim went into the pit three days later to do work in the clean pit. "But the concentrations of hydrogen sulfide were still high enough in that pit," she said.
Just as the industry saw eight months ago, the men were just doing their job. Going in after a dropped tool - or an unconscious son - seemed like the only option at the time, but it was this decision that left each of the men fighting a losing battle against hydrogen sulfide. Whatever the excuse or justification, the risk isn't worth it.
"We have to take precautions on the front end. We have to make sure we know what the conditions are where we're going," Andersen said.
It's not feasible to think that pork producers won't ever have to enter their pits.For those who do, here are precautions Anthony suggests to stay safe and alive:
- Educate and warn everyone on the farm. Post signs warning of the danger.
- Prevent accidental entry into the pit.
- Don't enter the hog barn during or after the manure has been agitated.
- If entering the pit is inevitable, ventilate the space thoroughly, have a retrieval system such as a harness in place or a person on stand-by to help pull you out, and use a selfcontained breathing apparatus.
Remember: Your nose will not be able to detect lethal levels of hydrogen sulfide. Monitors are highly encouraged.