I believe it is called Halotron, I had one in my Miata. The guy at the extinguisher store recommended it since it wouldn't throw powder everywhere and destroy an engine compartment. He never mentioned the lethality of it though. Are you saying a breath of the stuff would kill you or does it have to be inhaled continually?
You're right, the haylon replacement is "Halotron."
They said if you breath it in (haylon) you'll die - but I suppose its a matter of volume (haylon to air ratio in your lungs). Like CO2 it displaces oxygen, but its better at it. It is directed and heavier than air, so as long as you don't shoot it at someone or in a confined space (like maybe in the car while someone is in it), I assume its safe - I guess you weigh which way you want to die.
Maybe you could stop by your local fire station and ask? They must know.
Dry chemical in your lungs just gets coughed out.
They said if you shot a CO2 extinguisher in someones face it will freeze their air passages (dead tissue now) and suck all the air out of whats left of their lungs.
Water extinguisher have an anti-rust chemical in them that can damage eyes (if it gets in them).
If you can find an ABC rated foaming one, that would be the best (i've only seen AB foam - no C and C is electrical). No chance of inhalation and it prevents re-ignition.
Again, here are the ratings:
Class A Class A fire extinguishers are used on fires involving ordinary combustibles, such as wood, paper, cloth, rubber and some plastics.
Class B Class B fire extinguishers are used on fires involving flammable liquids such as gasoline, oils, diesel fuel, grease, paints, thinners, etc.
Class C Class C fire extinguishers are designated as Class C denoting that the agent in the fire extinguisher does not conduct electricity. Class C fires involve energized electrical equipment
Class D Class D fire extinguishers are used on fires involving combustible metals such as magnesium, titanium, aluminum, etc.
Class K Class K fire extinguishers are used especially in the kitchen for cooking oil and grease fires involving kitchen appliances.