Halon/BCF
Halon 1301 (usually used for flood systems) is more 'toxic' than 1211, However both are only 'toxic' with prolonged exposure and in extremely confined spaces. (greater than 20% volume)
1211 is the product found in cockpits/cabins. Interestingly for all the hand-ringing eco-facists out there, still worried about ozone depletion, when discharged onto a fire source the flouride components (which depletes ozone) is transformed and made inert in the chemical reaction which is responsible for the awesome fire extinguishing properties of BCF/Halon.
In my car I use an AFFF (aquious film forming foam) extinguisher (because I have too!!).
In my Helicopters I use only BCF/Halon.
I wont let Powder extinguishers in the offices/hangar let alone in my aircraft.
Basically Powder extinguishers work by bonding to any hot surface and also displacing oxygen. Its much finer than talcom powder and chokes like hell. It blocks your nose and throat with 'instant' white boogey's and it does a wonderful job of sticking to the wet part of your eyes!!!!
Let one of these off in a cabin and you can imagine what its like.
The original poster should thank his engineers for prompting this question and get those nasty Powder extinguishers away from your aircraft ASAP!!
Any hint that BCF/Halon should be removed from Aircraft - RESIST STRONGLY.