A sneeze is a common, involuntary reflex that protects the body. This rapid expulsion of air from the lungs through the nose and mouth clears irritants or foreign particles from the respiratory tract. Sneezing is a coordinated biological event designed to maintain nasal hygiene.
The Astonishing Speed of a Sneeze
The air and expelled particles from a sneeze can achieve remarkable speeds. While older estimates suggested speeds as high as 100 miles per hour, recent studies indicate a range of velocities. Research using high-speed cameras observed sneeze velocities around 10 miles per hour (4.5 meters per second) for the main air plume. Individual particles or strands of mucus can accelerate faster, reaching 30 to 80 miles per hour (14 to 35 meters per second). This forceful expulsion generates significant momentum.
The Powerful Physiology of a Sneeze
The force behind a sneeze results from a complex physiological process. The reflex begins with irritation of the nasal lining, sending signals via the trigeminal nerve to the brainstem’s “sneeze center,” which coordinates subsequent events. A deep inhalation draws air into the lungs, and then chest, diaphragm, and abdominal muscles contract powerfully, building pressure. Simultaneously, the soft palate and the uvula, which is the fleshy tissue hanging at the back of the throat, depress to partially close the passage to the mouth. This action helps direct the pressurized air primarily through the nasal cavity, maximizing the expulsive force and enabling rapid ejection of irritants.
The Far Reach of Sneeze Droplets
The expelled air from a sneeze carries respiratory droplets that can travel considerable distances. These droplets vary in size, from less than 1 micrometer to over 1000 micrometers. Larger droplets tend to fall quickly, but smaller aerosolized particles can remain suspended for minutes to potentially weeks. Studies show sneeze droplets can reach distances of 6 to 8 meters (about 20 to 26 feet), with some fine particles traveling up to 25 feet. This extended range is influenced by the turbulent gas cloud that accompanies a sneeze, carrying small droplets further than gravity alone would allow. This travel distance underscores their potential role in transmitting airborne substances.
Protecting Others: Sneeze Etiquette
Proper sneeze etiquette is important to reduce germ spread. Covering your mouth and nose when sneezing is a simple yet effective measure, with the recommended method involving sneezing into a disposable tissue, which should be immediately discarded. If a tissue is not available, sneezing into the crook of your elbow is a better alternative than using your bare hand. Sneezing into your hand can transfer germs to surfaces and other people through direct contact. Following a sneeze, washing hands thoroughly with soap and water or using an alcohol-based hand sanitizer helps to remove any lingering particles and minimize potential transmission.