UW–Extension describes silo gas as capable of causing “serious injuries — severe respiratory distress, permanent damage to lungs, and even death.”

State Rep. Travis Tranel (R–Cuba City) can personally attest to the part about “severe respiratory distress.”
Tranel spent four days in the hospital last week after he breathed in silo gas while working on his two Town of Hazel Green farm silos the morning of June 24.

“Normally silo gas is more prevalent right after you fill it,” said Tranel from his hospital room late last week. “I could just feel a little tickle in my stomach.”

After morning chores, Tranel drove to Boscobel to assist in flood recovery efforts. That night, he went to Platteville for an event. After a while, he said, “I told my wife I had to leave, because I couldn’t talk to people without coughing.”

They went home and to bed. Tranel awoke at 4 a.m. still having breathing problems, which, he discovered, got far worse when he stood up.

“I told her I had to go in [to the hospital] — I couldn’t stand and breathe at the same time; I could only breathe lying down,” he said. “That was not how I expected my Monday to go.”

A healthy adult should have a blood oxygen level of at least 95 percent. Low blood oxygen is defined as a blood oxygen level below 90 percent.

When he got to the hospital, a blood draw revealed that Tranel’s blood oxygen level was 56 percent.

“The doctor said I avoided the long sleep by coming in,” said Tranel. “So it was pretty serious.”

Silo gas, which forms when forage is put into a silo, includes nitrogen oxide and carbon dioxide. According to UW–Extension, nitrogen oxide becomes nitrogen dioxide — “a highly corrosive, toxic gas” that displaces oxygen — when combined with oxygen. When inhaled, the nitrogen dioxide mixes with a body’s moisture to form nitric acid, which causes burning and scarring of the lungs and other parts of a person’s respiratory system.

Because silo gas is heavier than air, silo gas will settle on the surface of silage, and travel down silo chutes, according to UW–Extension.

People exposed to silo gas can collapse and die from lack of oxygen upon breathing in silo gas. Others have been known to die hours later from pulmonary edema caused by the burning of silo gas.

Tranel was in intensive care and on oxygen for several days. When interviewed Friday, Tranel was still coughing and said he couldn’t breathe deeply, but, he said, “They’ve all said I’ll make a full recovery.”

Tranel’s hospitalization meant that he was unable to return to Boscobel for Gov. Scott Walker’s visit Wednesday, during which he declared a state of emergency for Grant, Crawford,  Richland and Iowa counties due to flood damage.

“I’d never thought I’d be in [a hospital] bed at 27,” said Tranel. “As a farmer, I don’t like being in confined spaces. I’m looking forward to getting out and getting some work done.”

Silo gas

To prevent silo gas exposure, UW–Extension recommends:

Stay out of the silo for two to three weeks after filling. This is the peak period of silo gas formation. Keep the silo room closed off from the rest of the barn, and ventilate it to remove any gas that flows down the chute.

Before you enter the silo for the first time, run the forage blower for 30 minutes, and leave it running while inside.

Ventilate the chute and silo room as well.  Have someone with you outside the silo to go for help if needed.

If you must enter the silo to level off or set up an unloader after filling, do so immediately after the last load is in. Do not wait until after supper or the next day. The blower should be running while you are inside.

Be aware that the forage blower air may not adequately ventilate a partly filled silo, since silo gas settles down on the surface.  Leave silo doors open to allow gas to escape, but be sure to close off and ventilate the silo room.
Invest in portable gas monitors to test for nitrogen dioxide and oxygen levels.  This is the only way to be certain the atmosphere is safe to enter.