Smell.

One of the 5 normal human senses. Smell.

Sometime you can shut your eyes to escape see what you do not want to see. Other time you can cup your ears to what you don't like to hear. However try holding your breath for more than just a few seconds. You can't right. The average person cannot do that for more than a minute.

As long as you are breathing, a minute amount of air will bring the scent particle up your nostrile. Wah la ... you smell. The mouth and nose are linked.

Haa