The Origins of the 100 Mph Myth
The idea of the high-speed sneeze has been around for decades, popularized by news reports and viral internet content. Early estimates were based on flawed or incomplete data, and the dramatic 100 mph figure was likely a result of sensationalism, similar to the myth that humans only use 10% of their brains. The forceful, convulsive nature of a sneeze certainly makes it feel fast, but perception often misleads reality, especially when reliable scientific measurement was less accessible.
What the Science Says About Sneeze Velocity
Modern scientific research has provided a much clearer picture of how fast a sneeze really is. Using high-speed cameras and advanced imaging techniques, researchers have captured the fluid dynamics of sneezes in action. These studies consistently show maximum air velocities that are far below 100 mph.
The Massachusetts Institute of Technology Study
One of the most referenced studies, conducted at MIT by Lydia Bourouiba, utilized high-speed imaging to analyze sneezes. This research, and subsequent work, found that the expelled droplets travel at a more moderate speed. The studies focused on how germ-laden plumes travel through the air, and while they can cover significant distances, the initial maximum velocity is in a much more believable range. One key finding is that the plume doesn't just shoot out and fall, but rather, stays suspended and travels much further than previously thought.
Other Research Findings
Other independent studies have corroborated these findings, with estimates of maximum sneeze velocity often falling between 10 and 40 miles per hour. Variations exist due to factors like body size, lung capacity, and the nature of the irritant. While a 40 mph sneeze is still a respectable speed—faster than many sprinters—it is a far cry from the speed of a cheetah or a race car, as some comparisons suggest.
The Anatomy of a Sneeze
To understand why the 100 mph figure is so inaccurate, it's helpful to look at the process of a sneeze itself. It is a complex reflex involving multiple muscles and parts of the nervous system. The trigger, often an irritant in the nasal passages, sends a signal to the brain's sneeze center in the medulla oblongata. The body responds with a coordinated series of actions:
- A deep inhalation: The lungs fill with air to prepare for the expulsion.
- Muscle contraction: The diaphragm and chest muscles tighten, building up pressure in the chest.
- Pressure release: The soft palate and tongue move to block the passage to the mouth, forcing the pressurized air to be expelled primarily through the nose at high speed. The final "achoo!" sound is the result of the explosive release of air.
Comparison of Sneeze and Cough Speeds
| Feature | Sneeze | Cough |
|---|---|---|
| Function | Expel irritants from nasal passages | Expel irritants from lower respiratory tract |
| Mechanism | Rapid, convulsive expulsion through nose and mouth | Forced expulsion from the lungs through the mouth |
| Maximum Speed | ~10-40 mph (per scientific studies) | ~50 mph (often faster at peak) |
| Primary Outlet | Nose, and often mouth | Mouth |
| Droplet Count | Can be over 100,000 droplets | Can be over 3,000 droplets |
How to Properly Cover a Sneeze
Given the germ-spreading potential of even a moderate-speed sneeze, proper etiquette is crucial for public health, especially during cold and flu season. The CDC recommends covering your mouth and nose with a tissue when you cough or sneeze. If a tissue isn't available, using the inside of your upper sleeve is preferable to using your hands, which can transfer germs to surfaces. Immediately washing your hands with soap and water for at least 20 seconds is the best practice after sneezing.
The Real Danger of Holding a Sneeze In
While the speed isn't a danger, suppressing a sneeze can be. Holding in a sneeze forces the high pressure created during the reflex back into the body, which, though rare, can cause harm. Potential injuries include:
- Ruptured eardrum: The pressure can travel up the Eustachian tube and damage the delicate eardrum.
- Throat injury: In very rare cases, suppressing a sneeze has been linked to rupturing the throat's lining.
- Broken blood vessels: The sudden spike in pressure can cause tiny blood vessels to burst, particularly in the eyes, which can result in redness.
Conclusion: The Truth is Less Dramatic, But Still Impressive
The truth behind the question, do sneezes go 100 mph?, is that the actual speed is significantly slower than the popularized figure. While the 100 mph myth makes for a dramatic story, the reality is still a powerful and fascinating biological process. A sneeze is an effective protective reflex, and modern science has not only corrected its top speed but also provided a deeper understanding of how we can better protect ourselves and others from the spread of germs. Learning the facts reminds us that even with everyday human functions, there's always more to discover about the complex and amazing workings of the human body.
For more information on the proper etiquette for coughing and sneezing, you can refer to authoritative sources like the Centers for Disease Control and Prevention CDC on cough and sneeze etiquette.
What to do if you need to sneeze but can't
Sometimes, the urge to sneeze is there, but the sneeze never comes. To encourage a sneeze, you can try stimulating the trigeminal nerve. A few gentle twists of a tissue in your nostril can often trigger the reflex. Another method is looking at a bright light, a phenomenon known as the photic sneeze reflex or 'ACHOO' syndrome, which works for about 18-35% of the population. These are simple, safe ways to clear your nasal passages when needed.
