A potentially dangerous chlorine gas leak from an industrial tank in Hilo sickened two people last week, but the Hawaii County Fire Department issued no public warning.

A Hawaii County fire official said Wednesday that in hindsight the department should have notified the public when a leak occurred two days in a row at the plant of fertilizer distributor BEI Hawaii on Iolani Street.

“Although we didn’t have readings outside or along the perimeter, it would have been good to notify the public we have an active incident going on,” fire Battalion Chief Gerald Kosaki said by telephone. “In the event that the incident should escalate, we may be conducting an evacuation. So when they see our guys walking around in hazmat suits, they know what’s going on.”

Last Thursday morning, a 120-pound chlorine cylinder was found to have sprung a slow leak from the valve stem. The company detected the problem after an air monitor showed the leak between 0.1 and 2 parts per million (ppm).

Employees investigated using a hand-held monitor and found the leaking cylinder at the back of the warehouse, Kosaki said. They placed the cylinder in a sealed containment vessel known as a “coffin.”

A fire department hazardous materials team arrived at 7:58 a.m. and took readings around the boundaries, but found no hazard.

At 20 feet from the vessel, they found a 0.1 ppm reading. Right at the coffin door, it was 30 ppm, but a foot from the door, it was 1.7 ppm.

Short-term exposure limit (15 minutes) for chlorine is 5 ppm without ill effects. Ten ppm is immediately dangerous to life and health, officials say.

The fire department consulted the state Hazard Evaluation for Emergency Response Office, which determined it would be best to place the leaking vessel in water. The leaking vessel was dipped into a water bath. Hazmat readings were safe, and the fire department left at 10:34 a.m.

At 6:26 a.m. Friday, the fire department was called back.

The plant manager had arrived at the facility to check on the chlorine bath and was overcome by fumes because the water had become saturated, and it started to emanate into the air, Kosaki said. He was checked out by a medic and taken to Hilo Medical Center.

The containment vessel was moved into a bigger water bath, so it could be totally submerged.

The initial reading by the plant manager was 22 ppm.

One Hilo resident, who lives about 100 feet from the plant, reported being sickened Friday.

County Civil Defense interim Administrator Ed Teixeira met Monday with the resident, who said he had difficulty breathing and was dry-heaving. He said he covered his face with his T-shirt, alerted his neighbor, then went to the fire command post to report what was happening. His wife then took him to Hilo Medical Center, where he was treated and released.