The answer may be simply that because we expel air from our mouths horizontally and only subsequently breathe in vertically through our nose, the chance of getting a representative whiff is low.

• 因此，答案也许很简单。因为口腔的气体是以水平方向迸出的，之后才有可能由垂直方向进入鼻孔，因此要能真正吸入足量口臭分子的机会实在不大。