Internal medicine, pulmonary disease, and critical care medicine specialist Dr. Mike Hansen, MD says most airlines are requiring passengers to wear masks: "Some airlines are also taking other measures to minimize person to person interaction," he says, "such as not serving alcoholic beverages or are skipping snacks altogether. Most commercial flights these days have very clean cabin air. Airplanes accomplish this by the way they have their air intake system setup. Essentially, they have compressed air passing through the jet engines, with its temperature being super hot. That hot air is then cooled, and put under pressure (450) PSI. So between the initial hot temperatures and the high pressure, that makes the air in the cabin very sterile, as bacteria and viruses become destroyed in that process."

Hansen says the cabin air is exchanged every 3-4 minutes, "which is actually better than offices and homes, which is typically every 5-12 minutes. Also, with newer generations of airplanes, they have high-efficiency particulate air filters, meaning HEPA filters, that filter the recirculated air. They can fish out particles as small as 0.3 microns, which is what an N95 respirator mask can do, as well as an elastomeric mask. Now some might say, well the virus is only about 0.1 microns in diameter or 100 nm…. And this is true. But most of the virus in the air is going to exist within respiratory droplets. So the bottom line is, if the virus is in the air, most of it, about 95% of it, will be filtered out with these HEPA filters on the plane, and the same goes for respirator masks.

"When someone is expelling respiratory droplets, the ones that are more than 5-10 microns in size, those are the ones that are going to act like ballistics, and fall within 6-12 feet of them, IF… they are NOT wearing a mask. The respiratory droplets that are expelled are less than 5 microns, these are the ones that will stay suspended in the air. If someone is wearing a mask, it will drastically reduce the distance the size of that moist cloud, and the distance that moist cloud can travel, but it won’t be totally prevented.

"So if no one sitting close to you, or if someone is sitting close to you but does not have the virus, no worries. But, of course, people are going to be close to you, and it's impossible to know who has the virus. And if that virus is in the air close to you, you’re going to breathe it in, unless….you do tip #1, which is, you wear an N95 respirator mask, or an elastomeric respirator. Both of these filter out at least 95% of airborne particles as small as 0.3 microns. Right now the CDC recommends the public to not purchase and wear these N95 respirator masks, for one because they need to be reserved for health care workers. I don’t understand how they can be in limited supply this deep into a pandemic, but I digress. But what you can do is get yourself an elastomeric respirator. This is a reusable device with exchangeable cartridge filters. Like an N95 respirator, it also filters out at least 95% of airborne particles as small as 0.3 microns. It fits tight against the user's face but is more comfortable than an N95."