The average speed of a sneeze is about 100 miles per hour, as noted by WebMD. Each sneeze packs a germy wallop, too, with each sneeze sending about 100,000 germs flying through the air.
A sneeze is a nervous system reaction to an irritant. The nerves tell the body there is something that needs to be quickly expelled from the body, and the body sends it out in the form of a sneeze. The causes of sneezes are not always dangerous to the body, as in the case of germs or allergens, even though the body perceives them that way, things as benign as bright sunlight or physical activity can trigger fits of sneezing.