Sneezing allows your nose or airway to get rid of an irritant, like smoke or dust, says Vijay Ramakrishnan, who is a professor at the University of Colorado Anschutz Medical Campus. Usually, it’s a sign of irritation, not infection. “The nose is basically the initial filter that separates your lungs and respiratory system from the environment,” he explains, trapping pollutants and irritants from the air.