Posted By Tyler Dry powder is corrosive to both metal and skin. It is widely known to produce symptoms similar to those you describe. It seems as though they may have used the extinguisher in a confined space and so have inhaled some of the powder. These extinguishers are best suited to larger areas or outdoor usage.

Posted By Geoff Burt I wasn't aware that there were dangers with powder extinguishers and the data sheets referred to by Jane don't seem to support that contention. Where is your information from Tyler?

Posted By Jane Blunt I agree with John that there are a lot of compounds in use in dry powder extinguishers. Before researching this subject I always thought that they were sodium bicarbonate. However, beware of falling into the trap of looking up the wrong chemical - boron may well be used in extinguishers - but is it in the form of the element boron, or a compound? You really need to know, because compounds are different from the elements from which they are formed. There is a substance that we put on our chips that contains a metal that reacts violently with water and a green poisonous gas (used for mass destruction in war-time) - I refer of course to common salt, which has neither of the aforementioned properties. Even if you inhale a powder that is harmless, it is going to take your body some time to clear the lungs. Jane