On Sept. 7, someone set off the release of 4,500 pounds of fire-suppressant halon-1301 gas in the Charleston County records center warehouse. This was bad news for two reasons: For one, halon is not cheap, and taxpayers might have to pony up $95,000 to refill the tanks. For another, halon is a known ozone killer.

The leak provided an opportunity for the county to consider switching its in-house fire-suppression system to a modern alternative with fewer environmental risks. But for now, Director of Internal Services Michael Filan says the county is investigating the leak and sticking with good ol’ halon, which is slowly being phased out of use since the 1994 Montreal Protocol called for chemical companies to halt its production. Halon, first used on aircraft in the 1960s, is useful for fighting fires near important documents and sensitive electronics because it leaves no residue.

The county keeps 10 cylinders full of the gas on hand to protect its records center on Leeds Avenue. When someone went through the multistep process of releasing the gas, the entire county’s supply was lost to the atmosphere.

Alternatives to halon, bearing such catchy monikers as HCFC-22, Foam A, and C6-perfluoroketone, promise the fire-suppressant and non-residual properties of halon without its environmental impact. Filan says the county has considered making a switch, but ultimately the price tag is the deciding factor.

“It would be more costly to replace the entire agent transport infrastructure and control system,” Filan wrote in an e-mail. He estimates that a new alternative-gas system would set the county back more than $250,000; the cost of refilling the existing halon system is about $95,000. The county has filed an insurance claim that might cover the refill.

The movement to wean businesses and governments off of halon began in the late 1980s, when it was discovered that the gas could damage the earth’s protective ozone layer. Bromine, one of the three elements that go into a halon molecule, gets released by photons from the sun and then sets off reactions that destroy ozone molecules. Since production of the gas stopped in the ’90s, the Environmental Protection Agency has decided not to outlaw halon use, as there is still a large supply left that gets sold and resold around the world. Tom Cortina, executive director of the nonprofit Halon Alternatives Research Corporation, says the decision to switch over from halon is entirely left up to the customer.

“In most cases, the halon is going to be maintained best, environmentally, by keeping it in a storage system,” Cortina says. “If you force it to be taken out, then you have this whole management problem: What are you going to do with all this halon? It’s expensive to destroy it.”

If anybody is going to preach the gospel of halon alternatives, it is Cortina. Since 1989, his organization has promoted the development and approval of replacement chemicals. But he says halon probably still has a few decades left as a useful product. In aviation, he says, it is still the industry standard. And while the global supply has been gradually dwindling since production stopped in 1994, he says the price has not skyrocketed. Part of the reason is the European Union’s ban on most uses of halon after 2003, which led to a glut in resold halon coming from European markets. In some cases, he says, the decommission of halon systems led to the unnecessary release of the chemical into the atmosphere.

In the United States, halon is still a feasible option for fire suppression. Most companies and governments, Cortina says, did not instantly rip out and replace their halon systems in the ’90s, although new fire suppression systems are being built to use alternative chemicals. Eventually, though, the supply will run out. At some point, Charleston County will have to bite the bullet and make a switch.

“It is legal to maintain the existing system,” Cortina says. “But if you have a hazard that you’re going to be protecting for 10 to 20 years, you may want to make the switch to the alternative for fear of you running out 10 to 20 years from now.”