The National Safety Council issued a public-health alert to warn farmers in
three Midwestern states of an increased risk of illness and death from exposure
to nitrogen oxide and nitrogen dioxide gas in farm silos. The increased health
risk to farmers is a direct result of drought conditions in parts of Iowa, Minnesota,
and Nebraska.
"Reports from portions of these three states indicate that drought-stressed
corn is being harvested for silage at an increased rate over the past few weeks,"
said Dr. Sam Steel, an agricultural safety expert with the NSC. "Under
the late summer drought conditions found in some of these regions, the vegetative
parts of corn plants may contain higher than normal levels of nitrogen. This
may translate into more concentrated levels of nitrous oxide and nitrogen dioxide,
commonly known as 'silo gas.'"
Steel said that farm families and workers must monitor their exposure to silo
gas as crops ferment in a silo.
"Fermentation begins within four hours of filling a silo and can continue
for up to 10 days," he said. "During this time, workers should not
enter an upright silo. Exposed individuals may suffer eye irritation, the onset
of fatigue, and a nagging cough, or nausea. High levels of silo gas exposure
may result in the delayed onset of symptoms, sometimes as long as 30 hours after
the initial exposure. In extreme exposure cases, silo gas will induce immediate
distress with the possibility of collapse and death within minutes."
NSC recommends these safe-management practices when dealing with fermenting
corn silage:
- Stay out of recently-filled silos and watch for symptoms of excess silo
gas. Silo gas is heavier than air and will quietly move down the ladder chute
of an upright silo. A bleach-like odor and the presence of a yellowish-brown
gas around the base of a silo are strong indicators of the presence of silo
gas. Dead insects and birds at the base of a recently filled silo may also
indicate the presence of dangerous silo gas.
- Use a blower to ventilate silos at least 30 minutes prior to entry. If the
danger of silo gas still exists, use a respiratory protective device such
as a self-contained breathing apparatus (SCBA).
- Never allow children or young family members to climb on or explore silos.
- Keep all doors between the base of a silo and ground level barns closed
to limit the amount of silo gas that can enter.