The Claim That Sneezes Reach Speeds of 400–460 Kilometers Per Hour.
Does the speed of particles coming out of the mouth and nose during sneezing can exceed 400 kilometers per hour and reach up to 460 kilometers?
What is the Reality?
In most cases, the speed of the particles that the average person can eject during a sneeze is 4.5 meters per second, which is around 16 kilometers per hour. Depending on the size, gender, lung capacity, illness/health condition, and sneeze strength, this speed can vary.
Origin of the Claim
The belief that the speed of a sneeze can reach hundreds of kilometers per hour is based on indirect calculations made in the 19th and 20th centuries.
For example, mid-20th century calculations by the American scientist and hygienic engineer William F. Wells concluded that the speed of a sneeze could reach 360 kilometers per hour (100 meters per second).
However, these are based on an indirect measurement of the droplets that can be formed on a liquid surface by particles scattered by a sneeze.
This number (and other values such as speeds of 120, 150, and 200 kilometers per hour) became popular due to the widespread reporting of such indirect measurements, while modern techniques calculate speeds much lower than this.
To date, a number of direct and indirect measurements of the sneezing rate have been made. The results of some of these measurements are compiled below.
In a study conducted in 2013 with 6 subjects and high-speed cameras, the distance and duration of the sneeze were measured by projecting LED light on the sneezing area of the participants sneezing in front of a concave mirror and measuring the diffraction amounts and distances of this light.
In this study, it was observed that the particles coming out of the mouth during sneezing can reach a maximum speed of 4.5 m/s (16 km/h).
In another study conducted in 2013, the sneeze speed was measured to be 6 m/s (21.6 km/h).
In 2014, in sneezing experiments conducted with human participants, with machines that are analogs of experiments, and with theoretical methods, the speed of the particles coming out of the mouth was measured to be around 1 meter per second (3.6 km/h).
In another 2015 study, it was observed that 3-centimeter particles were dispersed at a speed of 35 meters per second (126 km/h), while particles between 160 microns and 1 millimeter were dispersed at a speed of 14 meters per second (50 km/h).
In 2016, it was measured that particles scattered during a sneeze are ejected at a speed of 1–8 meters per second (3.6–28.8 km/h).
Of course, it should be noted that sneeze velocity is only indirectly related to how far the potentially disease-causing particles scattered by sneezing are spread. Sneeze velocity should only be seen as the average speed of the particles. It should also be remembered that particles of different sizes can reach different speeds and travel different distances.
No matter how fast the particles leave the mouth, very small particles, such as aerosols, can be suspended in the air and carried for many meters.
- L. Searing. The Big Number: 6 To 8 Feet — That’s How Far Germs Can Fly After You Sneeze Or Cough. The Washington Post
- WebMD. Sneezing: Myths, Causes, And Surprising Facts. WebMD
- P. Bahl, et al. (2020). An Experimental Framework To Capture The Flow Dynamics Of Droplets Expelled By A Sneeze. Experiments in Fluids, pg: 1–9
- J. W. Tang, et al. (2013). Airflow Dynamics Of Human Jets: Sneezing And Breathing — Potential Sources Of Infectious Aerosols. PLOS ONE, pg: e59970
- H. Nishimura, et al. (2013). A New Methodology For Studying Dynamics Of Aerosol Particles In Sneeze And Cough Using A Digital High-Vision, High-Speed Video System And Vector Analyses. PLOS ONE, pg: e80244
- L. Bourouiba, et al. (2014). Violent Expiratory Events: On Coughing And Sneezing. Journal of Fluid Mechanics, pg: 537–563.
- B. E. Scharfman, et al. (2016). Visualization Of Sneeze Ejecta: Steps Of Fluid Fragmentation Leading To Respiratory Droplets. Experiments in Fluids, pg: 1–9
- L. Bourouiba. (2016). A Sneeze. Massachusetts Medical Society, pg: e15
“Not yet a Medium Member? Join now with my referral link and Earn Income From Writing Just 5 Min/Day About Your Thoughts & What You Love to do! You’ll also get full access to every story on Medium for just $5/mo. Your membership fee supports independent writing. I’ll earn a small commission and no additional cost to you!
If you enjoy writing and storytelling, you can join Medium, Vocal as a creator to earn money and find your voice and reach out to a broad audience.