Use caution near the sides of the silo, especially if the silage is deeper than the height of the sides. Front end loaders should be kept low to reduce chances of overturns. Another place to exercise care at silage time is around upright silos. Fermenting silage produces nitric oxide, nitrogen dioxide, and nitrogen tetroxide. These gases can cause coughing, difficulty in breathing, or nausea.
Higher concentrations can cause the lungs to fill with fluid, resulting in death.
The presence of these gases is often indicated by dead birds or flies under the silo chute. The highest concentrations of these gases are produced during the first 48 hours after silage is added to the silo, but they may be present for the next four weeks. Avoid entering a silo for three to four weeks after silage has been added. If entry must be made during this time, ventilate the silo with the silage blower or ventilation fans for at least 30 minutes before entry and leave the fans on as long as someone is inside. Use a longer ventilation time if the silo is more than 24 feet in diameter or if the silage surface is more than 15 feet from the top of the silo.