This seems contradictory, because space is just an empty vacuum. Also, humans can't survive without being completely airtight in space. So how is it possible that we know? An ISS Science Officer explains that whenever he would operate the airlock for his crew mates in the international space station, he noticed a distinct smell.
He thought it was air ducts at first, but then he noticed it was stronger on their suits, tools etc. He describes it as "metallic; a rather pleasant sweet metallic sensation. It reminded me of my college summers where I labored for many hours with an arc welding torch repairing heavy equipment for a small logging outfit."