A private house in Auckland, New Zealand, recently blew apart and burned furiously for no apparent reason, badly injuring two men who were working in one of the rooms. News reports suggested that gas bottles were present and probably caused the explosion. Reports also mentioned that the men were sanding the floors. It will be interesting to see if investigations actually come up with the actual cause, which more than likely was due to a build up of dust in the air, due to a lack of ventilation and either a spark from some source, or the lighting of a cigarette, set off the explosion and started the fire. Any form of dust, concentrated in the atmosphere of an enclosed space can have devastating results when unknowingly ignited. Paint spraying can have the same results. See also HSE scenarios.