An airplane cabin can be a dirty place that easily allows for the spread of infectious diseases. Simple things such as washing your hands and covering your mouth when sneezing or coughing can help prevent the spread of germs. But did you know you have an even better chance of avoiding sickness if you use your air vent appropriately? Here's how.

Airplane Ventilation Systems

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When you are seated on an airplane, the air which comes through the little nozzle above your head, flows through the entire cabin, and exits through a grill found beneath the windows. This air mixes with outside air and then goes through a High Efficiency Particulate Air (HEPA) filter to remove 99.97% of dust and microbes before the air goes back into the airplane. These process happens 15 to 30 times per hour in each temperature control zone in the airplane. For comparison, air in an office building only gets recycled through a ventilation system about 10 times per hour.  About 50% of air is recycled and 50% comes from the outside in an airplane ventilation system.

Certain vacuum cleaners contain HEPA filters. These vacuums are common for those with pets or allergies because they successfully block dust and particles, reducing the affect on those who are allergic to pet hair, pet dander, and types of household dust mites. These HEPA filters emerged from early airplane ventilation systems. Airplane ventilation systems are actually much better than you think because they were designed when it was still legal to smoke cigars and cigarettes on flights. Engineers needed an efficient design that filtered the air so cabins weren't smoky. It's highly unlikely you will contract an illness from the recycled air on an airplane, but you still might be at risk for airborne pathogens.

Contracting an Airborne Pathogen on a Flight

In an interview with NPR, aviation medicine specialist Dr. Mark Gendreau explains the science of contracting and airborne virus on a flight. As previously mentioned, ventilation is important.

Airborne viruses include measles, tuberculosis, influenza, and others. According to Gendreau, they last in the air for up to five hours and get transmitted via tiny droplets. Droplets associated with upper respiratory infections and colds are often larger and heavier, so they don't stay airborne quite as long. In either case, when you are close to a person who is infected, you can easily contract whatever germ or virus he or she has from their sneezing, coughing, breathing, or speaking. In fact, heavy common cold droplets can travel up to six feet when someone sneezes, coughs, or simply speaks.

Airplanes also foster sickness because they are environments of low humidity, causing a person's mucous membrane to dry out, which makes them more vulnerable to contracting a virus.

Using Your Air Vent for Increased Protection From Illness

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When you are taking a flight to a tropical destination or flying domestically in the heat of summer, nothing feels better than the cold air from you vent while you are waiting for the captain to fire up the engines and turn on the A/C. Yet, the cold air coming out of those vents can be uncomfortable during the winter. According to Dr. Gendreau, and others who have studies germs on airplanes, you should always keep your vent on anyway.

No matter where you are sitting or who might be coughing or sneezing nearby, the air blowing from the vent creates an invisible barrier that blocks tiny droplets or particles which might contain viruses. Dr. Gendreau recommends angling the air flow so you can feel it on your hands while they rest in your lap. Not only does the air that has gone through a HEPA filter pass in front of your face, but it also helps blow heavy particles containing the common cold and germs, which might lead to upper respiratory tract infections, to the ground. Think of the airflow from the vent as a zone of protection that keeps airborne viruses from getting close to you.