Wear a close fitting mechanical filter respirator. It forms as a result of chemical reactions that begin almost immediately after chopped plant material is placed in a silo. Nitrogen dioxide is heavier than air and can flow out and settle near the ground. It may be visible as a reddish to yellowish-brown haze around the base of a recently filled silo. It has a characteristic bleach-like odor and leaves a burning sensation in the nose, throat and chest.
Nitrogen dioxide can result in instant death o permanent lung damage.
The first three weeks after filling a silo is when the risk of exposure is greatest. It replaces the air in the confined headspace of a silo. As with nitrogen dioxide, the risk of exposure is greatest the first three weeks after filling a silo. Due to risk of exposure to nitrogen dioxide and carbon dioxide, stay out of silos during filling and for three weeks, unless you wear an air-supplying respirator. If a silo must be entered, do it immediately after blowing the last load into the structure.