International space station astronauts pulled an alarm and donned protective gear on Monday after smelling a foul odour that turned out to be a vapour leaking from an oxygen vent, NASA said.
"Things are calming down," NASA spokesman Kelly Humphries said. The crew donned surgical gloves and masks but at no time did they have to put on a gas mask or oxygen mask, said Mike Suffredini, NASA's space station program manager.
The crew at first reported smoke, but it turned it to be an irritant, potassium hydroxide, which was leaking from an oxygen vent, Suffredini said.
"We don't exactly know the nature of the spill ... but the crew is doing well," Suffredini said. "It's not a life-threatening material."
The crew in the orbiting lab 220 miles (354 kms) above Earth was working on a Russian oxygen producing device known as the Elektron, NASA said.
The international space station was in the middle of a revolving door of visitors. Space shuttle Atlantis' six astronauts departed on Sunday and a Russian Soyuz vehicle carrying two new station crew members and space tourist Anousheh Ansari were expected to arrive on Wednesday.
Early on Monday, Atlantis astronauts attached a boom to the shuttle's robotic arm and started an inspection for damage to the shuttle's wings and nose. This is part of the post-Columbia accident routine for shuttles, in which, astronauts look for the type of heat shield cuts and tears that caused the fatal shuttle accident in 2003.
The inspection was being conducted by pilot Chris Ferguson and astronauts Dan Burbank and Steve MacLean while the shuttle stayed about 50 miles (81 ksm) away from the station in the same relative orbit.
If the astronauts find the type of damage that could cause a deadly accident, the shuttle can return to the station. Earlier inspections showed the heat shield was in good condition.
At the same time, astronauts examined and tried to fix what may be a minor leaky valve used for dumping water overboard. Mission Control praised Atlantis for completing its main mission of adding a 17 1/2-ton addition, including a pair of 115-foot-long (34.5-meter) solar wings, to the space station.