An evacuation order for residents was issued and then lifted in about 30 minutes after a report that white phosphorus had leaked at the K-55 U.S. military base (Osan Air Base) in Seotan-myeon, Pyeongtaek, Gyeonggi.
Pyeongtaek city sent a disaster text message at 6:13 p.m. on the 28th saying, "(Evacuation order lifted) The white phosphorus leak inside the K-55 U.S. military base has been handled within the unit. Nearby residents, please return to your daily routines." It came 36 minutes after the evacuation order text was sent.
At around 5:07 p.m. the same day, a report came in that white phosphorus had leaked at the K-55 U.S. military base. The U.S. military reportedly said it "suspects a chemical leak from a warhead."
At the time, white phosphorus had dripped from two white phosphorus warheads, and the amount leaked was not confirmed. White phosphorus can spontaneously ignite in air at around 30 degrees or higher. It causes severe burns if it touches human skin, and heavy inhalation of the smoke can be fatal.
After the report, fire authorities dispatched nine pieces of equipment and 31 personnel to the scene and responded with the U.S. military explosive ordnance disposal (EOD) unit.
However, the U.S. military reportedly told Pyeongtaek city that "the leaked white phosphorus is diluted by about 80%, so the risk to humans and the surrounding environment is low."
The U.S. military also told police that "a chemical used to wipe warheads leaked inside the K-55 ammunition depot, but it has now been contained and poses no danger."