During a kiln shutdown, industrial cleaning contractors were vacuuming dust from inside the kiln dust room. Suddenly a large amount of material poured into the room via the inlet chute, filling the air with a thick cloud of dust. All three contractors in the room managed to make their way to the exit. While doing so, one of the contractors stumbled and fell, which led to alkaline dust entering his eyes and respiratory system.
The cause of the inflow of material is thought to have been a blockage in the inlet chute that suddenly released itself while the contractors were in the room. This potential hazard had been underestimated during the planning and risk assessment of the job. With hindsight, it is recognized this assessment relied too heavily on the fact that this had never happened before rather than whether or not it could happen