The crew of Soyuz 21 had experienced pyschological and physical problems during their stay on the station. Although it was thought that this was mainly due to them becoming emotional, not following their physical training, and developing an unreasonable desire to return to earth, there was speculation that maybe some fuel had leaked into the living areas.
This prompted the Soviets to design equipment that could be used to completely change the air of the station by venting the atmosphere through the airlock. The equipment involved compressed air being released which created a breeze that blew the contaminated air out of the airlock.
When the crew arrived they found that the station atmosphere was completely fine and free of any toxins. It was decided to perform the experiment anyway to prove that it was possible in case the need ever arose in the future aboard other stations. Because of this the planned EVA was cancelled.
The mission was short by space station standards at only 18 days. The Soviets said however that it was a busy and successful mission, accomplishing nearly as much as the earlier Soyuz 21's 50 day mission.
The landing took place on February 25 when the capsule touched down 36 km northeast of Arkalyk, Kazakhstan.