There are many misconceptions surrounding how air moves around the confines of an aircraft cabin – when the reality is, the cabin air environment on an aircraft is probably cleaner than that in many confined spaces because modern airplanes have cabin air filtration systems equipped with HEPA filters. HEPA or high efficiency particulate air filters have similar performance to those used to keep the air clean in hospital operating rooms and industrial clean rooms. These filters are very effective at trapping microscopic particles as small as bacteria and viruses. They are effective at capturing greater than 99% of the airborne microbes in the filtered air. The majority of modern, large, commercial aircraft, which use a recirculation type of cabin air system, utilise HEPA filters. A small number of older aircraft types have filters with lower efficiencies.
How does it work? Well, while you may have been previously led to believe that cabin air circulates from take off until landing without the introduction of fresh air, this is not the case. Fresh air is continuously introduced during the flight, on some aircraft such as the A350 XWB it’s every 2-3 mins. The cabin air is constantly flowing, fresh air enters via the top of the aircraft, passes through the HEPA filters and is pushed down to the floor, meaning the air in the aircraft does not stay stagnant.Last updated: September 30 2020 10:08 PM
As the ‘new’ air enters the cabin from outside, the same quantity of ‘used’ air from the cabin is expelled overboard via the pressurisation outflow valves, such that it is fully renewed/exchanged with fresh air about every two to three minutes. For comparison, air in hospital rooms and classrooms is exchanged about every 10 minutes and about 20 minutes in offices. The fresh air from outside the aircraft is naturally free from any pathogens at the high cruising altitudes where airliners operate.
Scientists agree that HEPA filters are highly effective at capturing everything from viruses to skin flakes, but the problem, explained by various scientists, is that passengers can still breathe in tiny floating droplets from another passenger seated nearby – before the air carrying those droplets can be vented out of the cabin and filtered – this is why, for extra protection, airlines have now implemented mandatory mask policies for all passengers and crew onboard.
HEPA filters and mandatory mask policies are pushing down Covid-19 risks for air travel, but testing is one of the only strategic options available to the air travel sector that is likely to make the most significant difference.
Rapid and affordable antigen tests that can be administered by non-medical staff are expected to become available in “coming weeks” and should be rolled out under globally agreed standards, IATA’s CEO Alexandre de Juniac reiterated.
With rapid antigen tests becoming available for as little as $7 each, De Juniac said, airlines will push for their use to be endorsed by International Civil Aviation Organisation (ICAO), the UN agency that oversees global aviation rules.
Production could be quickly increased 2mn per day and the tests phased in between late October and the end of the year.
Last-minute airport screening is more effective because it “seals off the system” against forged certificates or infections contracted just before travel, De Juniac said on Tuesday.
Antigen tests are faster but less sensitive and therefore slightly more likely to miss positive cases than the PCR alternatives, although the accuracy gap has narrowed over the last few months.
Among companies marketing the new tests, German diagnostics specialist Qiagen said earlier this month it planned to launch a Covid-19 antigen test that provided results in 15 minutes and could be deployed in airports.
Antigen tests look for pieces of proteins that make up the Sars-CoV-2 virus to determine if the person has an active infection. In most cases, a nasal or throat swab is taken by a healthcare provider and tested. A positive antigen test means that the person being tested has an active Covid-19 infection. It can be used to quickly determine who has an active infection, can help identify people who are contagious to others, and is a less expensive test than PCR.
Airline leaders continue to view Covid-19 testing as one of the few strategic options that has the ability to reduce further damage to the already suffering global air travel sector.
While Asia has been quick to adopt testing for air travel, it’s only just starting to be implemented over in the US. American Airlines is collaborating with several foreign governments to begin offering pre-flight Covid-19 testing for customers travelling to international destinations, starting with Jamaica and the Bahamas. The carrier plans to expand the programme to additional markets in the weeks and months ahead.
“The pandemic has changed our business in ways we never could have expected, but all the while, the entire American Airlines team has eagerly tackled the challenge of reimagining the way we deliver a safe, healthy and enjoyable travel experience for our customers,” said Robert Isom, President of American Airlines. “Our plan for this initial phase of pre-flight testing reflects the ingenuity and care our team is putting into rebuilding confidence in air travel, and we view this as an important step in our work to accelerate an eventual recovery of demand.”
American has been working with the government of Hawaii to develop a series of options that fit the Hawaiian requirements for travel to the state. Starting October 15, the airline will begin a pre-flight Covid-19 testing programme at its Dallas Fort Worth International Airport (DFW) hub for customers travelling to Hawaii, in partnership with companies LetsGetChecked, CareNow and the DFW Airport.
Beginning this month, American will offer three options for pre-flight testing to customers with flights from DFW to Honolulu and Maui: At-home test, observed by a medical professional via virtual visit, with results expected in 48 hours on average. Alternatively, in-person testing at an urgent care location, or onsite rapid testing, administered at DFW.
Testing must be completed within 72 hours of the final leg of departure. Travellers who test negative will be exempt from the state’s 14-day quarantine.
*The author is an aviation analyst. Twitter handle: @AlexInAir