@AndoniP,
Halon has been banned globally because it makes holes in the ozone layer, while FM200 (which is also an haloalkane and works in the same way as Halon to extinguish fires) does not.
However, aircraft fire extinguishers are exempt from the ban because Halon is better suited for this application. I believe this is due to its lower boiling point: at -20°C, a Halon bottle will still work but a FM200 bottle won't, since at that temperature FM200 is a liquid.
There is no significant difference in toxicity between Halon and FM200. Both are quite innocuous at the concentrations typically employed (< 10%).