Empty Middle Seats on Planes Cut Coronavirus Risk in Study

Leaving the center seats vacant during a flight could reduce passenger exposure to coronavirus in the air by 23 to 57 percent. This is what researchers reported in a new study that modeled how aerosolized virus particles spread in a simulated aircraft cabin.

“Next is always better in terms of exposure,” said Byron Jones, a mechanical engineer at Kansas Sate University and co-author of the study. “It’s true in airplanes, it’s true in cinemas, it’s true in restaurants, it’s true everywhere.”

However, the study may have overestimated the benefits of having empty center seats by ignoring the wearing of masks by passengers.

“It’s important for us to know how aerosols spread in airplanes,” said Joseph Allen, a ventilation expert at Harvard TH Chan School of Public Health who was not involved in the study. But he added, “I am surprised that this analysis is now being published and it makes a big statement that the center seats should be left open as a risk mitigation approach if the model does not take into account the effects of masking. We know that masking is the most effective measure to reduce emissions from inhalation aerosols. “

Although scientists have documented several cases of coronavirus transmission on airplanes, airplane cabins are generally low risk environments as they tend to have excellent ventilation and filtration.

Still, concerns about the risk of air travel have swirled since the pandemic began. Planes are tight environments, and full flights make social distancing impossible. As a precaution, some airlines have started keeping the center seats free.

The new paper, published Wednesday in the Weekly Report on Morbidity and Mortality, is based on data collected at Kansas State University in 2017. In this study, the researchers sprayed a harmless aerosol virus through two mock aircraft cabins. (One was a five-row section of an actual single-aisle aircraft, the other a model of a wide-bodied double-aisle aircraft.) The researchers then monitored how the virus spread in each cabin.

For the new study, researchers from the state of Kansas and the Centers for Disease Control and Prevention used the 2017 data to model how passenger exposure to a virus in the air would change if each middle seat was in one 20-row entrance cabin would remain open.

Depending on the specific modeling approach and the parameters used, keeping the middle seats empty reduced the overall load on the passengers in the simulation by 23 to 57 percent compared to a fully occupied flight.

This reduction in risk resulted from increasing the distance between an infectious passenger and others, as well as reducing the total number of people in the cabin, reducing the likelihood that an infectious passenger would be on board at all.

The laboratory experiments on the spread of viruses in aircraft cabins were conducted several years before the current pandemic began and did not take into account any protection that wearing masks could provide.

Masking would reduce the amount of virus infectious passengers release into cabin air and would likely reduce the relative benefit of keeping the center seats open, said Dr. Everyone.

Dr. Jones agreed. “In general, I would think that wearing a mask would make this effect a lot less pronounced,” he said. He also noted that mere exposure to the virus does not mean that anyone will be infected by it.

The cost-benefit analysis is difficult for airlines. However, from a purely health perspective, keeping the center seats open would be helpful to create a buffer between an infectious person and others nearby, according to Alex Huffman, an aerosol scientist at the University of Denver who was not involved in the study . “Removal is important, both for aerosols and for droplets,” he said.