Looks like it is safe:

"It is a common misconception that halon "removes oxygen from given space." This is what C02 does, not halon. According to the Halon Alternative Research Corporation (www.harc.org): "Halons are low-toxicity, chemically stable compounds that have been used for fire and explosion protection throughout this century. Today, Halon 1211 (a liquid streaming agent) is used mainly in hand-held fire extinguishers and Halon 1301 (a gaseous agent) is used mainly in total flooding systems. These halons have proven to be extremely effective fire suppressants, which are clean (leave no residue) and remarkably safe for human exposure. Three things must come together at the same time to start a fire. The first ingredient is fuel (anything that can burn), the second is oxygen (normal breathing air is ample) and the last is an ignition source (high heat can cause a fire even without a spark or open flame). Traditionally, to stop a fire you need to remove one side of the triangle - the ignition, the fuel or the oxygen. Halon adds a fourth dimension to fire fighting - breaking the chain reaction. It stops the fuel, the ignition and the oxygen from dancing together by chemically reacting with them. Many people believe that halon displaces the air out of the area it is dispensed in. Wrong! Even for the toughest hazards, less than an 8% concentration by volume is required. There is still plenty of air to use in the evacuation process."


The EPA recognizes that that halon remains the most effective extinguishing agent available, and it continues to allow its use despite its ozone depleting potential. All halon available now is recycled, so it is not an environmentally irresponsible choice. In addition, due to its effectiveness and relatively low toxicity, the FAA also continues to require halon extinguishers for use on commercial aircraft.

Finally, there are no federal or state regulations prohibiting the buying, selling or use of halon extinguishers."