In this exercise, attention is paid only to the exhalation, not the inhalation. The entirety of the exercise is to breath out through the nose imaging that there is a feather just outside the nose. The intention is to disturb the fine hairs of the feather as little as possible, without becoming uncomfortable.
Rationale Like many breathing exercises, the idea here is to lengthen exhalation without being too mechanical about it. Leaving the inhalation alone is part of interfering with natural breathing as litle as possible. Using the nose increases awareness of breathing
Source: Majid Ali, MD