When we breathe through the nose, the dust particles, smoke, etc. get stuck in the hair present in the nose, which act as filters. But if we breathe through the mouth, all the dust will enter our body system.

When we breathe through the nose, the dust particles, smoke, etc. get stuck in the hair present in the nose, which act as filters. But if we breathe through the mouth, all the dust will enter our body system.