Why do we often sneeze when we inhale a lot of dust-laden air?
Sneezing expels the foreign particles from the inhaled air, so that only clean air enters our body. It usually occurs because of the irritation in the upper breathing passage. This irritation happens when we inhale some unwanted particles and they get trapped in our nasal cavity. Smoke, dust, pollen, etc. are some of the unwanted particles that may cause sneezing.
We often sneeze when we inhale a lot of dust-laden air to expel out these foreign particles. These particles get past the hair in the nasal cavity and irritate the lining of the cavity which results in sneezing.