I don't know what "metal screens" mean in Oz, but here in the US they are a wire gauze used to keep insects out and let breezes in. If they are solid we'd call them "metal shutters".

Sorry, Rapaire. I didn't get to see your latest post before sending my previous bit in. Gauze screen (whether wire or plastic) in Oz are routinely referred to as "flywire"; the metal screens your man is using appear to be what you'd call shutters.

The main use of CABA (as it's called in Oz) by firefighters (again, in Oz) is to provide a breathable atmosphere while inside smoke- and fume-laden atmospheres such as you find inside a burning structure. The local town brigades across NSW maintain they have an average response time of 4 minutes. Research here indicates that, within 2 minutes of a flame appearing from fuel that is smouldering, atmospheres inside a structure will become toxic from vapourisation of flammable materials; plastic degrades to produce cyanide and hydrochloric acid fumes, and any hypalon exposed to such temperatures can produce hydrofluoric acid. None of these is good for one's health, which is why evacuation drills specify completion within 90 seconds; it's also a good reason to wear CABA if you must enter such atmospheres.

Cheers, Rowan