Why do people sneeze?

When we breathe in unknown particles, our noses and sinuses detect the objects. The nose does this 24/7 but sometimes it has to 'reboot'.

During the sneeze, we reset our nasal environment (just like a reboot) and after the reset it can continue detecting the particles we breathe in. We humans aren't the only species that sneeze, animals like cats, dogs & even chicken can sneeze to reset their nasal system.

Fun fact: The average sneeze speed is 160 km/h (100mph)