As more people return to the airways, questions are being raised about the risk of COVID-19 infection from flying in an enclosed aircraft with a cabin full of strangers. In-flight air filtration is fast and effective against bacteria and viruses, including COVID-19. A new study revealed the chances of becoming infected with COVID-19 while wearing a mask and flying on a modern, commercial airline is about the same as being struck by lightning, about one chance in half-a-million. 

That’s good news since travellers are starting to fly again, and the number of trips by individuals is steadily rising. In April, 3.2 million travellers passed through the Transportation Safety Administration’s (TSA) security screening, representing about four percent of the number from a year earlier. In October 2020, that number topped 24 million.  

The air filtration and recycling on a jet is fast and effective due to the use of powerful air circulation fans and high-efficiency particulate absorbing (HEPA) filters.  

“The HEPA filters are 99.9% effective or greater in removing particulate contaminants, including viruses like COVID-19, and bacteria and fungi from recirculated air. The air flows from the ceiling to the floor and creates completely new air in the cabin every six minutes,” said Denise Stecconi, a commercial pilot who flies Boeing 737s for Alaska Airlines.  

These air filters can remove very small particles such as bacteria and viruses. The most difficult particles to remove are miniscule, ranging in size from 0.1 to 0.3 microns, but HEPA filters easily filter out these very small particles with an efficiency level of 99.995%. The coronavirus measures 0.125 microns, well within the capture range of a HEPA filter. 

Stecconi referred to a recent Harvard study when she explained how outside air comes into the jet’s fuselage and is directed through a compressor near the engine and then is pushed through a series of heat exchangers to get it to the right temperature. From there the cabin air filtration begins when the air is moved by two large on-board fans. There are floor grilles on the sides of the passenger cabin. The air goes through the HEPA filters and the filtered air goes back into the air conditioning mix manifold.  

“Those fans are so powerful that it only takes six minutes to completely renew the air in in the cabin. As a pilot, that gives me great peace of mind for my safety and the safety of my crew and passengers,” Stecconi said. 

The study showed that particulate matter lasted in a jet cabin less than six minutes, on average, which is significantly less time than in most residential homes where it took about an hour and a half to cycle the air. 

Stecconi added that your pets flying in the cargo bay are also breathing HEPA-filtered air when they’re onboard large, modern, commercial jets. “The air that goes into the aft cargo compartment comes directly from the cabin, so this means its cleaned as well by the HEPA filters.”  

But not all planes have HEPA filtration systems. According to the International Air Transport Association (IATA), the majority of modern, large, commercial aircraft using recirculation types of cabin air systems utilize HEPA filters. But a small number of older aircraft types have air filters with lower efficiencies. 

Stecconi added that smaller, regional jets might not have HEPA filters but since they’re pressurized aircraft they will have air conditioning packs and recirculation systems to move the air collected through the engines into the cabin and then back out relatively fast. Unpressurized aircraft don’t have these types of air filtration systems either, like smaller helicopters.  

Travelers can check airline websites to determine what kind of aircraft they expect to fly and what it’s air filtration and circulations capabilities are. Whatever kind a plane you may board during the pandemic wearing a mask, physically distancing and sanitizing your hands and high-touch areas remain the best ways to minimize your risk of infection.  

Matt Napiltonia is a former pilot and Senior Manager in Global Rescue’s US-based Operations Center.