What the heck is a HEPA filter? How airplane air stays clean
If you're traveling these days, airlines want you to know they're doing everything in their power to keep you healthy.
American, Delta, United and Southwest have all emphasized their in-depth cleaning procedures in e-mails to customers during the past week. All four airlines have also made a point to specifically note that many of their aircraft are equipped with high-efficiency particulate air (HEPA) filters.
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It's a piece of equipment you may have never heard of before this week, but now that it's become so high-profile, we figured you'd want to know everything you can about it. So, TPG reached out to R. Eric Jones, an associate professor and chair of the Aviation Maintenance Sciences Department at Embry-Riddle Aeronautical University. The conversation has been edited for length and clarity, and some contextual information from other sources is included in brackets.
What are HEPA filters?
HEPA filters are a very high-intensity system of fibers that you essentially run air through to filter out an incredible amount of contaminants — not just dust, not just bacteria, but moisture, any sort of contamination that could potentially harm or create an atmosphere in the cabin or the cockpit that could harm the passengers or the crews. The material in them is much closer together compared to cheaper air filters, and that makes it very difficult for biological elements to penetrate them.
How common are HEPA filters?
I don’t know of an airline that’s operating right now that does not have HEPA-level filters on them, but that does not mean that one does not exist. There’s a certain amount of air quality that you have to maintain in your commercial airplane. If you’re flying commercial passengers or corporate passengers, you’re going to have a HEPA filter or better air filtration system.
Related: The most up-to-date information about airlines' coronavirus waivers and schedule changes.
Just to be clear, these HEPA filters are also on high-end vacuums and other commercial air filtration systems. They’re not exclusive to the airlines or the airline experience, they’re used in lots of areas of your everyday life.
[Commercial airlines in the U.S. need to maintain minimum cabin air quality standards set by the Federal Aviation Administration. HEPA filters are the most common way to meet those guidelines, but some aircraft use other approved methods.]
How effective are HEPA filters?
The airlines are trying to do everything they can to mitigate the spread of these viruses.
[According to the Centers for Disease Control and Prevention, HEPA filters capture 99.9% of particles (bacteria, fungi, and larger viruses or virus clumps) 0.1–0.3 micrometers in diameter, and cabin air generally passes through the filters 20-30 times per hour.]
Related: Everything you need to know about traveling during the coronavirus outbreak.
The airlines started to put in HEPA filters because they are effective, but they will only protect you from airborne viruses or bacteria. If you touch a tray table, a HEPA filter is not going to help you. There is a misperception that the public feels that "I got sick on an airplane because I breathed air that is filled with a virus,” but normally, it’s from touching hard surfaces that haven't been cleaned properly.
How are HEPA filters maintained?
They do need to be changed, but it's a very simple job. You just go into a panel, pull out the old filter and put in a new one. Every airline has what's called an operations specifications manual, and that dictates how that airline runs, including how often components are changed. There's some variation in how often they're changed, but it's been my experience that those HEPA filters are changed more frequently than what the manufacturers require.
HEPA filters are also made by a number of manufacturers, and each may have its own maintenance guidelines.
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Cons
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- Some may have trouble using Uber and other dining credits
- You may be eligible for as high as 100,000 Membership Rewards® Points after you spend $6,000 in eligible purchases on your new Card in your first 6 months of Card Membership. Welcome offers vary and you may not be eligible for an offer. Apply to know if you’re approved and find out your exact welcome offer amount – all with no credit score impact. If you’re approved and choose to accept the Card, your score may be impacted.
- Earn 4X Membership Rewards® points per dollar spent on purchases at restaurants worldwide, on up to $50,000 in purchases per calendar year, then 1X points for the rest of the year.
- Earn 4X Membership Rewards® points per dollar spent at US supermarkets, on up to $25,000 in purchases per calendar year, then 1X points for the rest of the year.
- Earn 3X Membership Rewards® points per dollar spent on flights booked directly with airlines or on AmexTravel.com.
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- $120 Uber Cash on Gold: Add your Gold Card to your Uber account and get $10 in Uber Cash each month to use on orders and rides in the U.S. when you select an American Express Card for your transaction. That’s up to $120 Uber Cash annually. Plus, after using your Uber Cash, use your Card to earn 4X Membership Rewards® points for Uber Eats purchases made with restaurants or U.S. supermarkets. Point caps and terms apply.
- $84 Dunkin' Credit: With the $84 Dunkin' Credit, you can earn up to $7 in monthly statement credits after you enroll and pay with the American Express® Gold Card at U.S. Dunkin' locations. Enrollment is required to receive this benefit.
- $100 Resy Credit: Get up to $100 in statement credits each calendar year after you pay with the American Express® Gold Card to dine at U.S. Resy restaurants or make other eligible Resy purchases. That's up to $50 in statement credits semi-annually. Enrollment required.
- $120 Dining Credit: Satisfy your cravings, sweet or savory, with the $120 Dining Credit. Earn up to $10 in statement credits monthly when you pay with the American Express® Gold Card at Grubhub, The Cheesecake Factory, Goldbelly, Wine.com, and Five Guys. Enrollment required.
- Explore over 1,000 upscale hotels worldwide with The Hotel Collection and receive a $100 credit towards eligible charges* with every booking of two nights or more through AmexTravel.com. *Eligible charges vary by property.
- No Foreign Transaction Fees.
- Annual Fee is $325.
- Terms Apply.