So, it's 1211 and 1301 that are outlawed. You can actually buy recycled 1301 still, much like freon, but it's very expensive. Halon 1211 is cool because it doesn't displace the oxygen so you can still breathe in a space filled with it. 1301 was less effective so more had to be used, enough to begin displacing oxygen. So, since we have halon 1301, when the alarm goes off, get the hell out of the engine room.