You probably already know that covering your mouth when sneezing or coughing is more than just good manners, but a necessity when trying to keep cold, flu and other viruses far away. A new study released by researchers at MIT, entitled “Violent expiratory events: on coughing and sneezing,” published in the Journal of Fluid Mechanics, found that coughs and sneezes have “…gas clouds that keep their potentially infectious droplets aloft over much greater distances than previously realized.” Because germs are now travelling further and higher, sometimes even to the ceiling, indoor ventilation systems may be playing an unwitting role dispersing infectious particles over a wide area.
“When you cough or sneeze, you see the droplets, or feel them if someone sneezes on you,” says John Bush, a professor of applied mathematics at MIT, and co-author of a new paper on the subject. “But you don’t see the cloud, the invisible gas phase. The influence of this gas cloud is to extend the range of the individual droplets, particularly the small ones.”
Bush said that the purpose of the cloud is to literally push out the droplets from the sneeze or cough. “…the smaller droplets that emerge in a cough or sneeze may travel five to 200 times further than they would if those droplets simply moved as groups of unconnected particles — which is what previous estimates had assumed,” according to Bush and the associated study. Many of the study’s conclusions may change what was previously known about coughs and sneezes and the spread of germs and disease.
“You can have ventilation contamination in a much more direct way than we would have expected originally,” says Lydia Bourouiba, an assistant professor in MIT’s Department of Civil and Environmental Engineering, and co-author of the study.
In order to study the trajectory and gas clouds that follow a sneeze or cough, researchers used a combination of high-speed imaging of coughs and sneezes, as well as laboratory simulations and mathematical modeling, to produce these new findings.
This study could have far reaching implications beyond healthcare science, but also in engineering, architecture and indoor air quality technology. Scientists and entrepreneurs are developing innovative ways to respond to the growing body of scientific research changing our understanding of the spread of germs and disease.
For example, several years ago, researchers at Kansas State University and University of Cincinnati validated the effectiveness of ActivePure technology for reduction of particulate in the air and contaminants on surfaces, reducing or eliminating virtually all organic and microbial compounds, bacteria and viruses where we live and breathe. The technology directly addresses many of the concerns about germs and viruses highlighted by researchers in the MIT study.
As we learn more about the spread of germs through coughing and sneezing, these breakthrough technologies can reduce the spread of airborne and surface pathogens and contribute to a healthier home and office.