Drought Fuels Deadly Silo Gas
A deadly threat is looming on many farms in the Northeast this fall in the form of a caustic gas built up in silos full of corn and chopped hay.
Silo gas is a potentially deadly byproduct of the natural fermentation of feed for farm animals. It's at higher levels this fall in areas that had an unusually dry summer, according to agricultural authorities. Farmers are used to dealing with the pungent gas, but haven't seen levels like this in several years.
"Filling and unloading silos always require care, but this year, due to the dry weather we have experienced, the threat of silo gas is even greater than normal," said state Agriculture Commissioner Nathan Rudgers. "The safety recommendations are critically important."
Rudgers and state Health Commissioner Dr. Antonia Novello have warned farmers to take extra precautions, including not entering the silo immediately after filling, using blowers and calling emergency personnel for anyone who is overcome.
Silo gas - actually nitrous dioxide - results from the natural fermentation of farmers' corn and hay, which is richer in nitrates after a dry summer. Yellowish or orange colored, the gas has a bleach-like odor.
The gas is most concentrated in the first 24 to 72 hours after a silo is filled, but remains hazardous for about three weeks. The gas can injure even if it isn't concentrated enough to smell or see, Novello said.
Most states rich in agriculture report deaths from silo gas every year or two, including would-be rescuers. Even a breath or two can cause lung injury as the gas dissolves into the moisture of lungs and forms nitric acid, which burns and causes the lungs to fill quickly with fluid. High concentrations of silo gas can cause death in seconds, Novello said.
The gas, which is heavier than air, can also seep out of a silo and cause injury if inhaled a few feet around the silo.
Federal workplace regulations state that air with 50 parts per million of nitrogen dioxide is an "immediate hazard" to life and health. Silos recently filled with feed can have levels as high as 10,000 parts per million, said Arlene Clark, a nurse who works at a clinic for farmers with the Center for Agricultural Medicine and Health, a regional service for farmers from Maine to West Virginia.
"It's just so shocking because we all live on farms," said Patrick Hooker, a 40-year-old Herkimer County farmer who also works for the New York Farm Bureau. Between himself and his wife, Karen, their families have been in farming for a couple hundred years.
"Hardly a fall goes by where somewhere in the state we don't see a report of it," he said. "I certainly recall it numerous times in my short career. ... It's the kind of thing that just sneaks up."
Many farms have large fans or blowers that help dissipate the gas and many silos have mechanical "levelers" to spread the feed evenly, limiting the need for farmers to enter.
"I can see how it happens," Hooker said. "Equipment breaks and you shimmy up the silo to see what's going ... people are in a hurry and they just forget that you have to run the blowers."
Other times, even experienced farmers will try to save time by using a pitchfork to level out the silage as it's poured in. "Well, people don't come out of that sometime," he said.
"I think the awareness is kind of a double-edge sword," said John Shutske, an agriculture safety specialist at the University of Minnesota. "I think we get used to working around those hazards, but you find yourself in a situation where you've been doing it 10 or 20 or 50 years, and then you have a fatality."
By Michael Gormley