Corralling Airborne Germs in an Airliner Cabin

The mighty manufacturers of airliners, like Airbus and Boeing, should be embarrassed. A 17-year-old high school student has developed a way to keep germs from spreading in the cabin of an airliner. Countless highly-compensated aerospace engineers have not advanced cabin health as much as one teenager.

An airline cabin is the most densely-packed public area in 21st century society. More than concert halls, sports arenas, restaurants, hospitals, supermarkets, or any other place where people congregate, an airplane cabin confines each passenger to a telephone-booth-size area in which such items like arm rests and seat-back trays are not cleaned with disinfectant between flights. The cabin is a veritable Petri dish full of micro-organisms, some of which cause colds, flu, or worse. Being seated next to someone with a cold spewing small droplets of mucous with each hacking cough means exposure from which there is no escape.

The "puffer" vents do not provide sterile air

The “puffer” vents do not provide sterile air

Maybe there is some relief in sight. Raymond Wang, a Canadian high school student, received the top award at the 2015 Intel International Science and Engineering Fair last month in Philadelphia. He beat out 1,700 students from 78 countries with his device for improving cabin air circulation in airplanes. For his invention, he won the $75,000 Gordon E. Moore Award.

“With the traditional cabin, what’s happening is you’ve got two large, turbulent swirls happening. You’re spreading disease across the rows,” he explained.

Simply stated, there’s stagnant air inside the crowded aluminum tube, and when someone sneezes, there’s a “mess everywhere” — meaning that germs spread, he said.

Raymond Wang, covered in glory

Raymond Wang, covered in glory

Wang created computerized simulations of the air circulation inside a B737 cabin. He used those simulations to design devices that would fit inside an airplane’s existing air ducts; the small fins create a virtual “wall” around each passenger; the microscopic contamination from coughs and sneezes are pushed out of the cabin before they can spread in a turbulent burst.

Wang claims his device can be installed in the air vent with just two screws.

His prototype cost $10, and he estimates it would cost $1,000 to equip an entire airplane’s air circulation system. He may not appreciate the cost involved in qualifying something for use in an airliner, but at triple his $1,000 estimate, the benefits to passengers seem worthy.

Below is his explanation of the award-winning project:

“I tackled the issue of airborne pathogen spread in aircraft cabins, generating the industry’s first high fidelity simulations of airflow inside airplane cabins. Using my insights, I engineered economically feasible solutions that altered cabin airflow patterns, creating personalized breathing zones for each individual passenger to effectively curb pathogen inhalation by up to 55 times and improve fresh air inhalation by more than 190%.” [When this writer was a junior in high school, expressions like “high fidelity simulations” would not have come to mind.]

“Billions of people travel in airplanes annually, where isolated air in densely packed aircraft cabins can propagate disease via both direct airborne and large droplet routes … One group of researchers discovered that a passenger with H1N1 [influenza] could spread the disease to up to 17 other passengers per flight. Another group published a case study in which one SARS afflicted passenger had infected 22 others in a matter of three hours on a single flight.

A typical air-circulation system, which takes "bleed" air from the engines

A typical air-circulation system, which takes “bleed” air from the engines

“Millions of dollars have been invested into studying the exteriors of aircraft, aiming to improve factors like aerodynamics and fuel efficiency. Sadly, when we examine current research in the field of aircraft cabin airflow, we find that our understanding is largely incomplete. Because of the limited resolution of empirical measurement methods, CFD [computational fluid dynamics] analyses have come to be the preferred tools in industry. However, much of the existing work with aircraft cabin airflow, both commercially and in academia, is affected by critical errors: we find papers that have over-approximated the geometries of humans and cabin surfaces, models that have misplaced key cabin air inlets, and research that has failed to consider complex interactions between multiple physics. All of these factors add up to obscure the industry’s understanding of actual cabin airflow scenarios….”

“Every day after school, I’d spend at least three hours chugging away at my project. As I built up my confidence, I transitioned into modeling my own flow scenarios, beginning simulations with just an empty cabin, and gradually progressing in complexity…

“Through these simulations, what becomes evident is that the key issue with disease transmission occurs when a passenger sneezes inside the cabin. In a traditional cabin, airflow patterns can continually throw around the pathogen contaminants without providing them an opportunity to be absorbed by the HEPA filters in the air outlets near the bottom of the cabin.

“As this simulation demonstrates, pathogens from passenger effluents can continuously swirl around the cabin, passing by the neighbors’ breathing zones several times before ever reaching the outlets for filtration. And, while passengers are able to actively take measures, such as washing their hands, to avoid infection from contaminants on tray tables and other cabin surfaces, the effects of the global airflow situation in the cabin is significantly more difficult to counteract.”

Wang may be onto something with his concept of a “wall” of air around each passenger but, as he acknowledges, his revised airflow reduces pathogen contamination by only 55%, which leaves literally millions of pathogens to infect others as a portion of cabin air is recirculated. A steady flow of conditioned outside air would exact a fuel-burn penalty, so a portion of cabin air is sent repeatedly through the air-conditioning system.

However, intense ultraviolet light, located in the center of the air ductwork, would kill virtually all pathogens before they could be pumped into the cabin.

This pathogen-killing capability would require electric power equivalent to that of a kitchen microwave oven. Control could be automatic; when the air-circulation system is energized, the UV light in the plenum would come on, providing a reliable flow of sanitized air to the passengers.

Both technologies — Wang’s cabin airflow scheme and the irradiating UV light — would assure passengers of fresh air. Passengers might be uncomfortable in their cramped seating, but the air they breathe would not be a foul, pathogen-ridden miasma.