The legislation refers to the risk of asphyxiation arising from a free-flowing solid or being unable to reach a respirable environment due to being trapped by such a free-flowing solid. This could be due to the ingress of free-flowing solids.
Free-flowing solids have similar characteristics to liquids and can submerge a person, preventing breathing. These solids include grain, sugar, flour, sand, coal dust and other substances in powder or granular form, such as gravel or soil.
In a confined space, the risk is increased because there is no space for the material to flow away.
Some free-flowing solids may form combustible dust clouds when disturbed; this could present a risk of explosion, see Operations - Physical Hazards.
Knowledge and understanding
Understand all associated hazard knowledge