As airlines eagerly plan to resume business, the industry is gearing up to implement new safety regulations both at the airport and on board. In a recent report from Southwest Airlines, CEO Gary Kelly announced that the carrier will be decreasing seat sales to allow for greater in-flight social distancing. Last week, JetBlue announced that all passengers must now wear face protection on board. The European low-cost carrier WizzAir is following suit, by implementing strict cleaning procedures as it partially resumes service to London, Paris, Rome, and Barcelona.

While airlines may implement various rules, the key feature that they all share is the use of the HEPA filter, an air-filtration system that kills around 99.97 percent of airborne viruses. But what exactly is the HEPA filter and can it really guarantee that airline passengers will breathe clean, virus- or bacteria-free air?

What is a HEPA filter and how does it work?

A HEPA (high-efficiency particulate air) filter is a device made of extremely close-knit fibers that capture and remove impurities from the air. According to the Environmental Protection Agency, HEPA filters catch “at least 99.97 percent of dust, pollen, mold, bacteria, and any airborne particles.” Commonly used in spaces that require high sanitary standards, such as hospitals, the filter has been built into airplane cabins since the 1980s.

The Centers for Disease Control and Prevention (CDC) explains that airplanes built after 1980 recirculate up to 50 percent of cabin air by combining the internal air with external air, filtering the supply through the HEPA filter. On average, this process occurs every three minutes. Only particles smaller than 0.3 microns manage to pass through the device, meaning that the vast majority of contaminants are completely removed.

Airplane ventilation systems are typically set up to encompass seven to eight rows, which, in turn, makes sure that fresh, clean air circulates evenly. According to research conducted by Honeywell, a company that produces environmental control systems and cabin pressure technology for aircrafts, 44 percent of Americans worry that airplane air can make them sick. Yet experts say the air is not usually the source of contamination.

“Viruses associated with the common cold or upper respiratory tract infections are often too large and heavy to hang in the air,” said Dr. Mark Gendreau, director and vice-chair of emergency medicine at Lahey Medical Center, Peabody, in an interview with Travel and Leisure. Gendreau explained that such viruses quickly fall to the floor and other surfaces.

Even with HEPA filters, extra caution will be needed

Impeccably efficient, the HEPA filter kills bacteria, fungi, and virus clumps. What it does not protect against, however, is being sneezed on by a sick passenger or touching an infected tray table. This is why extra precautions will need to be put in place before travelers take back to the skies. A thorough cleaning of the aircraft with disinfectant after each flight is a new step toward safety, and so is the use of sanitizing wipes on board, which some airlines, such as JetBlue and WizzAir, are making complimentary for passengers.

The pandemic will certainly change the way we travel, and this may mean more independence and self-service for travelers. WizzAir encourages passengers to check in online at home three hours before their flight, as well as stand at least five feet apart in the boarding queue. Furthermore, Wizz passengers in Europe will be expected to drop off their own luggage and scan their mobile boarding pass. JetBlue is implementing changes to its in-flight service where crew members will now be expected to wear medical-grade gloves. “Buffer zones” will be designed and seats will be blocked out in order to provide more distance between passengers. Additionally, we’ll have to temporarily say goodbye to in-flight shopping and glass mugs, which will be replaced by single-use cups.