As travel slowly becomes a part of normal life again through the form of road trips and weekend excursions, the idea of getting on a plane in close proximity with strangers for a few hours still sounds like too much of a risk for many. A new study released this week, however, shows the risk of transmission is "virtually non-existent" during air travel—so long as every passenger wears a mask.
The study, conducted by the Department of Defense in a partnership with United Airlines, found that when all passengers are seated with a mask on, "only 0.003 percent of particles actually made their way into another passenger's breathing zone." The results of this study have not yet been peer-reviewed.
The study comprised around 300 tests using mannequins equipped with aerosol generators that mimic normal breathing and coughing. These generators released 180 million particles—equivalent to the number produced by thousands of coughs—with the mannequin's mask both on and off. The plane was equipped with more than 40 sensors able to detect the droplets, which represented other passengers that could theoretically come in contact with the particles.
The researchers found that wearing a mask limits the rate of transmission when a passenger is seated. Researchers did not attempt to replicate an infected person standing up or moving throughout a cabin, further spreading the droplets around, and it's important to note that the study did not account for time spent eating and drinking, which is when most passengers would remove their masks anyway.
"I'm not standing here telling people that I know exactly what they should do," said Josh Earnest, United Airline's chief communication officer. "What I am telling people is if you are inclined to travel or thinking about air travel, there is a reason today, based on this independent study, that you can feel confident that you can travel safely."
This study reflects earlier studies that found the airflow inside an airplane helps minimize risk. Commercial airplanes are equipped with HEPA filters, which capture and eliminate 99.97 percent of airborne particles, substantially reducing the risk of viral spread. The air inside of airline cabins changes over around 10 times an hour, giving them higher air quality than that of a normal building.
Experts say travelers should remain vigilant about wearing a mask throughout their travel, including airport security and throughout the terminal, and not just while on the plane.