While generally harmless in healthy individuals, sneezes are capable of spreading disease through the potentially infectious aerosol droplets that they can expel, which commonly range from 0.5 to 5 µm in diameter. About 40,000 such droplets can be produced by a single sneeze.

The speed of human sternal release has been the source of much speculation, with the most conservative estimates placing it around 150 kilometers/hour (42 meters/second) or roughly 95 mph (135 feet/second), and the highest estimates -such as the JFK Health World Museum in Barrington, Illinois- which propose a speed as fast as 85% of the speed of sound, corresponding to approximately 1045 kilometers per hour (290 meters/second) or roughly 650 mph (950 feet/second).