The US American Occupational Safety and Health Administration (OSHA) issued a
Hazard Alert about the deadly dangers to workers of engulfment and suffocation
while working inside grain storage bins. Grain bins are used to store bulk raw
agricultural commodities such as corn, wheat and oats.

Workers who enter bins can be engulfed and suffocated if they stand on moving
or flowing grain, which can act like "quicksand" and pull a worker under; if
they stand on or below "bridged" grain, which can collapse and bury workers; or
if they try to loosen grain, which can cave in on workers.

The Hazard Alert describes how workers may become engulfed in grain bins and
lists the precautions that employers must take under OSHA's Grain Handling
Facility standard to protect workers. These include disconnecting equipment
that presents a danger; prohibiting workers from walking on the grain to make
it flow; providing workers with personal protective and rescue equipment; and
requiring an observer outside the bin who can perform rescue operations.

More info

AplusA-online.de - Source: Occupational Safety and Health Administration