Keeping middle seats vacant during a flight could reduce passenger exposure to airborne coronavirus by 23 to 57%, researchers reported in a new study that modeled the spread of aerosolized viral particles through an airplane cabin simulated.
“Further afield 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 on airplanes, it’s true in movie theaters, it’s true in restaurants, it’s true everywhere.”
But the study may have overestimated the benefits of empty middle seats because it did not take into account the wearing of masks by passengers.
“It’s important for us to know how aerosols travel on 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’m surprised to see this analysis come out now, making a big statement that the middle seats should stay open as a risk reduction approach, when the model didn’t include impact. masking. We know that masking is the most effective measure to reduce respiratory aerosol emissions. “
Although scientists have documented several cases of coronavirus transmission in airplanes, airplane cabins are generally low-risk environments as they tend to have excellent ventilation and air filtration.
Yet concern has revolved around the risk of air travel since the start of the pandemic. Planes are confined environments, and full flights make social distancing impossible. Some airlines have started to keep the middle seats vacant as a precaution.
The new document, published Wednesday in the Morbidity and Mortality Weekly Report, is based on data collected at Kansas State University in 2017. In this study, researchers sprayed a harmless aerosol virus through two simulated airplane cabins. (One was a five-row section of an actual single-aisle plane; the other was a mock-up of a wide, two-aisle plane.) The researchers then monitored how the virus spread through each cabin.
For the new study, researchers from the State of Kansas and the Centers for Disease Control and Prevention used data from 2017 to model how passenger exposure to an airborne virus would change if each seat in the middle remained open in a 20-row single-aisle cabin.
Depending on the specific modeling approach and the parameters used, keeping the middle seats vacant reduced the total exposure of passengers exposed in the simulation by 23 to 57%, compared to a fully occupied flight.
“Some airlines have operated with a vacant seat policy, and this study supports the effectiveness of this intervention, against the backdrop of other measures that are in place,” a CDC spokesperson said in a statement sent by email.
This reduction in risk stems from increasing the distance between an infectious passenger and others as well as reducing the total number of people in the cabin, reducing the chances that an infectious passenger will be on board in the first place.
Laboratory experiments on the dispersion of the virus in aircraft cabins were carried out several years before the onset of the current pandemic and did not take into account the protection that wearing masks could offer.
The masking would reduce the amount of virus infectious passengers emit into the cabin air and likely reduce the relative benefit of keeping the middle seats open, Dr Allen said.
Dr Jones agreed. “In general, I think wearing a mask would make this effect much less pronounced,” he said. He also noted that just being exposed to the virus does not mean someone will be infected with it.
“The extent to which reducing exposure could reduce the risk of transmission is not yet understood,” the CDC spokesperson said.
Cost-benefit analysis is tricky for airlines. But purely from a health perspective, keeping the middle seats open would help, providing a buffer between an infectious person and others nearby, according to Alex Huffman, an aerosol researcher at the University of Denver who does did not participate in the study. “Distance matters, both for aerosols and for droplets,” he said.