The function of sneezing is to expel mucus containing foreign particles or irritants and cleanse the nasal cavity.
When sufficient external stimulants pass through the nasal hairs to reach the nasal mucus, it triggers the release of histamines. This irritates the nerve cells in the nose resulting in signals being sent to the brain to initiate the sneeze through the trigeminal nerve network. The brain relates this week initial signal and activates the pharyngeal and tracheal muscles, creating a large opening of the nasal and oral cavities, resulting in a powerful release of air and bio particles.
Sneezing is possibly linked to sudden exposure to bright light, sudden change in temperature, breeze of cold air, a particularly full stomach or viral infection and can lead to the spread of the disease.