- New research indicates that droplets containing the new coronavirus can travel as far as 18 feet after a person sneezes, coughs, and even speaks.
- Experts note, however, it still isn’t certain how long the new coronavirus can survive while airborne.
- They note the research does illustrate why it’s important to wear masks and maintain physical distancing while in public.
All data and statistics are based on publicly available data at the time of publication. Some information may be out of date.
While there’s still much to be understood about COVID-19, a recent batch of research is giving infectious disease experts some new information about the distance the new coronavirus can travel and how long it can linger in the air.
Researchers know the virus that causes COVID-19 is spread through respiratory droplets, namely from droplets that spread as we sneeze, cough, and even talk.
As people all over the world are practicing physical distancing, some recent studies are offering new evidence in the global health community’s response to a pandemic.
In a study published today in the journal Physics of Fluids, researchers Talib Dbouk and Dimitris Drikakis with the Defense and Security Research Institute at the University of Nicosia in Greece argue that with even a slight breeze — as little as 2.5 mph — it only takes 5 seconds for those tiny droplets to travel 18 feet.
The researchers used a “computational fluid dynamics simulation,” or software to simulate how fluid travels, to reconstruct how saliva droplets could travel from a coughing person.
The scientists took into consideration factors such as humidity, the force in which droplets are dispersed, evaporation, and how the saliva molecules interact with the air.
They reached their calculation of 18 feet in 5 seconds after running partial differential equations on 1,008 saliva droplets, solving about 3.7 million equations in total.
“This work is vital, because it concerns health and safety distance guidelines, advances the understanding of spreading and transmission of airborne diseases, and helps form precautionary measures based on scientific results,” Drikakis said in a press release.
Dbouk and Drikakis say more research is needed to better understand how things such as the temperature of the ground factor in. That also includes further studying indoor environments, where air conditioning would affect how those saliva particles travel.
Experts say this information could be useful when determining what kind of preventive personal measures — like wearing masks in public, physical distancing, keeping certain businesses closed longer — should be used until an effective vaccine is available.
While the research says saliva may be able to travel up to 18 feet, it didn’t address whether the new coronavirus would be able to survive long enough to travel and infect a person from that far away, according to researchers not associated with the study.
It also doesn’t show if or how long the virus lingers, which is a factor in other highly infectious diseases, such as measles.
Dr. Amesh Adalja, an infectious disease expert and senior scholar at Johns Hopkins Bloomberg School of Public Health in Maryland, says experts aren’t seeing that kind of infection with the new coronavirus.
“There’s still a lot of questions out there,” he told Healthline.
Jagdish Khubchandani, PhD, an associate professor of health science at Ball State University in Indiana, says the research in a simulation is “very good evidence,” given the difficulties of doing research on human participants during a pandemic.
“While we should have already used common sense, we have observed once in a while unintentional spitting or droplet ejection while talking or breathing,” he told Healthline. “It’s not uncommon.”
The next step, Khubchandani says, is to get real-world evidence that takes into effect things like how different types of interpersonal relationships, cultures, behaviors, and interactions would factor into transmitting the virus.
Other recent research indicates that normal conversation can leave infected oral fluid droplets in the air for as long as 14 minutes, according to research published May 13 in the Proceedings of the National Academy of Sciences.
Researchers at the National Institute of Diabetes and Digestive and Kidney Diseases and the University of Pennsylvania had study participants say “stay healthy,” and used highly sensitive lasers to illustrate that “loud speech can emit thousands of oral fluid droplets per second.”
“These observations confirm that there is a substantial probability that normal speaking causes airborne virus transmission in confined environments,” the researchers concluded.
That’s especially problematic for places where many people often talk loudly for extended periods of time, such as bars and nightclubs. That’s why so many governors have ordered those types of establishments closed.
That includes church choirs.
Following one meeting in early March that 61 people attended, there were soon 32 confirmed infections and another 20 secondary COVID-19 cases. Three people were hospitalized. Two died.
CDC investigators noted that being in close proximity to one another, sharing snacks, and putting chairs away after practice were all possible contaminating factors.
But singing loudly could have aggravated the spread.
“The act of singing, itself, might have contributed to transmission through emission of aerosols, which is affected by loudness of vocalization,” the CDC report says.
Khubchandani says the “reactive” approach to infectious disease spreading in light of COVID-19 “is one of the big reasons why the public is still suffering.”
“Even if we are able to do such research in a short span, how much new information can people get and use?” he said.
The CDC recommends — but does not require — that
It’s not necessarily because it’ll protect someone from breathing in the virus, but rather to keep potentially asymptomatic carriers from spreading the virus via the droplets we all exhale when we breathe, talk, cough, or sneeze.
For that reason, federal, state, and local leaders continue to encourage people to practice physical distancing — or remaining 6 feet apart from people who don’t live in your household — and refrain from large gatherings, such as live performances and church services.
But as more states decide how to safely reopen businesses and, soon enough, schools, experts say it’s going to be imperative to understand how to control the spread of the new coronavirus and others that will come after it.
That will most likely include the continued requirement that people wear face coverings while outside around other people, especially if they’re going to be breathing heavier by loudly talking, singing, or exercising.
Khubchandani says for activities such as hiking, if done with groups or in public places, or where population density is higher, “wearing masks is an absolute must.”
“We have generated enough evidence over the past few months to suggest that one of the best protective mechanisms are masks, and, maybe, it should become a part of life like watches, scarves, and other accessories,” he said.
But Adalja says using masks remain a point of dispute among the public.
“You’ll find people on both sides of this,” he said. “At this point, it’s going to boil down to a person’s preferences.”
Going forward, until a vaccine is readily available to the general population, Adalja says people will have to decide for themselves their risk for infection, because nothing is likely to change in the coming months other than the U.S. healthcare system’s ability to deal with new infections.
“This virus has established itself in the human population, and it’s not going anywhere in the absence of a vaccine,” he said.
While the federal government’s Operation Warp Speed is working to fulfill President Donald Trump’s goal of having a vaccine by January, Adalja and other experts are saying it’s more realistic that it would be 12 to 18 months before a vaccine is available.
“We have to be prepared to live without a vaccine,” Adalja said. “Nothing is going to make this virus magically disappear.”