Dr. David Powell, IATA’s Medical Advisor, calls the figures “extremely reassuring.” “Furthermore, the vast majority of published cases occurred before the wearing of face coverings inflight became widespread,” he notes.
A joint publication by Airbus, Boeing and Embraer explains the reasons behind the low transmission rate. Though aircraft types vary, detailed simulations confirmed that aircraft airflow systems effectively control the movement of particles in the cabin, limiting the spread of viruses.
High Efficiency Particulate Air (HEPA) filters, the natural barrier of the seatback, the downward flow of air, and high rates of air exchange efficiently reduce the risk of transmission.
HEPA filters, for example, have a more than 99.9% bacteria/virus removal efficiency rate, ensuring that the air supply entering the cabin is not a pathway for microbes. Air is exchanged 20-30 times per hour on board most aircraft, which compares very favorably with the average office space (average 2-3 times per hour) or schools (average 10-15 times per hour).
The publication and IATA’s data collection align with a peer-reviewed study by Freedman and Wilder-Smith in the Journal of Travel Medicine.
Mask-wearing adds an extra layer of protection. This was recommended by IATA in June 2020 and is now common on most airlines. The Takeoff Guidance issued by ICAO supports this approach. The guidance also adds numerous other layers of protection to keep transmission rates to a minimum.
“ICAO’s comprehensive guidance for safe air travel amid the COVID-19 crisis relies on multiple layers of protection, which involve the airports as well as the aircraft,” says Powell. “Mask-wearing is one of the most visible. But managed queuing, contactless processing, reduced movement in the cabin, and simplified onboard services are among the multiple measures the aviation industry is taking to keep flying safe. And this is on top of the fact that airflow systems are designed to avoid the spread of disease with high air flow rates and air exchange rates, and highly effective filtration of any recycled air.”
The simulations carried out by the three major manufacturers further highlighted the importance of aircraft design in low infection rates.
An Airbus simulation of the air in an A320 cabin calculated parameters such as air speed, direction and temperature at 50 million points in the cabin, up to 1,000 times per second. The same tools were then used to model a non-aircraft environment, with several individuals social distancing. The result clearly demonstrated that potential exposure was lower on an aircraft than when staying six feet apart in an office or classroom.
“After multiple, highly-detailed simulations using the most accurate scientific methods available, we have concrete data which reveals the aircraft cabin offers a much safer environment than indoor public spaces,” reveals Bruno Fargeon, Airbus Engineering and the leader of the Airbus Keep Trust in Air Travel Initiative.
Boeing researchers studied various scenarios, including a coughing passenger with and without a mask seated in various locations, and different on / off variations of overhead air vents.
“This modeling determined the number of cough particles that entered the breathing space of the other passengers”, says Dan Freeman, Chief Engineer for Boeing’s Confident Travel Initiative. “We then compared a similar scenario in other environments, such as an office conference room. Based on the airborne particle count, passengers sitting next to one another on an airplane is the same as standing more than seven feet (two meters) apart in a typical building environment.”
Embraer research likewise showed that risk of onboard transmission is extremely low, and the actual data on in-fight transmissions that may have occurred supports these findings.
“The human need to travel, to connect, and to see our loved ones has not disappeared,” says Luis Carlos Affonso, Senior Vice-President of Engineering, Technology and Strategy, Embraer. “In fact, at times like this, we need our families and friends even more. You can fly safely. All the research demonstrates this.”
A report by the United States Transportation Command (US Transcom) confirms the low risk of COVID-19 transmission onboard an aircraft.
The US Transcom testing, which was conducted in August 2020, found that “the overall exposure risk from aerosolized pathogens, like coronavirus, is very low.” More than 300 aerosol releases, simulating a passenger infected with COVID-19, were performed over eight days using United Airlines Boeing 767-300 and 777-200 twin aisle aircraft.
“The US Transcom research provides further evidence that the risk of infection onboard an aircraft appears to be very low, and certainly lower than many other indoor environments,” says Alexandre de Juniac, IATA’s Director General and CEO.
The US Transcom report states that aerosol particles remained detectable for less than six minutes on average. Both aircraft models removed particulate matter 15 times faster than a typical home ventilation system and 5-6 times faster “than the recommended design specifications for modern hospital operating or patient isolation rooms.” Testing was done with and without a mask for the simulated infected passenger.
The testing was conducted in partnership with Boeing and United Airlines, as well as the Defense Advanced Research Projects Agency (DARPA), Zeteo Tech, S3i and the University of Nebraska’s National Strategic Research Institute.
The research done on inflight transmission of the coronavirus demonstrates the cooperation and dedication to safety of all involved in air transport. It provides undeniable evidence that cabin air is safe.
Indeed, the priority on safety is no different during the COVID-19 outbreak. A recent IATA study found that 86% of recent travelers felt that the industry’s COVID-19 measures were keeping them safe and were well-implemented.
Alexandre de Juniac, IATA’s Director General and CEO, accepts that there is no “single silver-bullet measure” that will make air travel 100% safe in the age of COVID-19. “But the combination of measures that are being put in place is reassuring travelers the world over that COVID-19 has not defeated their freedom to fly,” he says. “Nothing is completely risk-free. But with just 44 published cases of potential inflight COVID-19 transmission among 1.2 billion travelers, the risk of contracting the virus on board appears to be in the same category as being struck by lightning.
“The detailed research of the aircraft manufacturers demonstrates that combining the aircraft’s existing design features with mask-wearing creates a low-risk environment for COVID-19 transmission,” he concludes. “As always, airlines, manufacturers and every entity involved in aviation will be guided by science and global best practices to keep flying safe for passengers and crew.”