According to NASA’s official blog a leak of the khladon gas (Freon-218), used in the air conditioning system has occurred at the Zvezda service module of the Russian segment of the International Space Station (ISS). "Samokutyaev and Serova performed steps to release pressure in the Russian Segment Air Conditioner System [СКВ] by venting Khladon (Freon 218) overboard. However, several of the quick disconnects that were actuated during the procedure exhibited leaks," NASA's blog entry reads. "As a result, the Khladon was vented into the cabin instead." But according to Irina Zubareva, the spokesperson for the Russian space agency Roscosmos, there have been no gas leaks on board the Russian segment of the ISS, she told TASS news agency.

“We do not confirm the NASA blog publication,” Zubareva said. “There were no gas leaks on the Russian segment.”

According to NASA, the quantity released was about 100g, which results in a density of 117 mg/m3 over the volume of ISS after about 2 hours, which was below the stated ISS zero risk flight rule limit of 150 mg/m3.  As part of nominal air scrubbing process, the Russian Air Purification System and the USOS Trace Contaminant Control System (TCCS) will remove residual Khladon from the atmosphere. Intermodule ventilation configuration was not changed as a result of this inadvertent release.

NASA’s office at Russian Mission Control near Moscow said it had no details of the situation at the moment. Russian specialists were holding a conference to discuss the incident.

Freon-218, or Octafluoropropane (C3F8) is a fluorocarbon non-flammable greenhouse gas. In the electronics industry, octafluoropropane is mixed with oxygen and used as a plasma etching material for SiO2 layers in semiconductor applications, as oxides are selectively etched versus their metal substrates. Under the name R-218, octafluoropropane is used in other industries as a component of refrigeration mixtures. It has featured in some plans for terraforming Mars. It is also the active liquid in PICO-2L dark matter bubble detector.