Are Viruses the Real Horror at 35,000 Feet?
The Spread of Respiratory Diseases in Flight
In 2018, a group of ten mathematicians conducted a study modeling how respiratory diseases can spread during flights at high altitudes. This research proved to be remarkably timely, as air travel has since been identified as a significant factor in the spread of the COVID-19 pandemic.
Concerns About Air Travel
Traveling by air can already be challenging due to dry cabin air, cramped economy seats, and unappetizing food. However, researchers are increasingly concerned that airplane cabins could serve as significant vectors for viral transmission. Following documented cases of SARS and H1N1 spreading on commercial flights, the possibility of infectious diseases spreading during air travel has become a pressing global health issue.
Each year, over 3 billion passengers take to the skies, and any one of them could be carrying an emerging infection. To investigate how diseases spread in airplane cabins, the research team monitored ten transcontinental flights in the U.S. Their findings were published in the Proceedings of the National Academy of Sciences.
Key Findings on Human Interaction
The team observed more than 1,500 passengers and discovered that human interactions were not random. This means that not all passengers faced the same risk of infection. As anticipated, crew members had the most interactions with passengers, particularly those seated in aisle positions. Notably, 80 percent of aisle seat passengers moved at least once during the flight, compared to just 43 percent of window seat passengers. This difference indicates that aisle seat occupants were significantly more likely to come into contact with an infectious individual.
How Do Viruses Spread on Planes?
Insights from Historical Data
Using data from a 1977 case study, which revealed that 38 out of 54 passengers and crew contracted an unknown influenza-like illness while trapped on a grounded aircraft, the researchers estimated that an infected passenger could cause about 0.7 new infections per flight. In contrast, an infected crew member could lead to as many as 4.6 new infections.
By analyzing passenger and crew behavior, the mathematicians predicted that individuals seated next to or one row away from an infectious person faced the highest risk of transmission, with a chance of infection ranging from 0.8 to 1 percent. The risk diminishes significantly when sitting farther away, dropping to below 0.02 percent.
Strategies for Minimizing Risk
For travelers seeking to reduce the likelihood of contracting a respiratory disease while flying, the study suggested that sitting by the window and away from the cabin’s center offers the best protection. Additionally, minimizing interactions with flight crew and limiting trips to the lavatory can further lower exposure risks.
Variability of Infection Risks
Factors Influencing Infection Rates
Infection risks can vary significantly from one flight to another, influenced by factors such as passenger composition, flight duration, cabin layout (single-aisle vs. double-aisle), and cabin disinfection protocols. To safeguard oneself and fellow passengers, maintaining regular hand hygiene is essential, and it is advisable to avoid flying when feeling unwell.
Study Reference
Calvin J. Chan, B.Sc.
Reference: Hertzberg, V.S., Weiss, H., Elon, L., Si, W., Norris, S.L. and the FlyHealthy Research Team. (2018). Behaviors, movements, and transmission of droplet-mediated respiratory diseases during transcontinental airline flights. PNAS. 10.1073.