It's an unfortunate fact that the more people there are around you in a crowded space in flu season, the more likely you are to encounter cold and flu droplets. "People with flu can spread it to others up to nearly six feet away," Dr. Kaiser tells Bustle. We can encounter flu viruses through inhalation, and people don't have to be sneezing to spread them; they may just be chatting to their friends. They may also may also be traveling before they know they're ill. "People with the flu become contagious one day before they actually have symptoms," Dr. Kaiser tells Bustle.

For this reason, communal areas in airports where there are many people in small spaces, like lines or shops, are particularly common areas for flu germs. "When stores are crowded, you are exposed to a higher number of possibly sick shoppers," Dr. Kristine Arthur M.D., an internist at MemorialCare Medical Group, tells Bustle. Holiday sales at duty-free will likely have a lot of flu germs in the air.

A Finnish study published in BMC Infectious Diseases in 2018 found that of all the surfaces in airports, communal luggage trays at security had the highest proportion of flu germs. Shared surfaces touched by thousands of people, experts tell Bustle, are particularly common places for flu germs, as the germs are transmitted by touch.

Dr. Arthur recommends that you wipe down shared surfaces with antibacterial wipes when you can to avoid viruses, but this likely won't be welcomed at security as it will slow down the line. It's likely best practice to use hand sanitizer, and wipe down things that have been in contact with trays before you put them back in your bag.

Communal airport surfaces that are designed to be activated by hand, like elevator buttons, bathroom locks, and hand rails on stairs and escalators, also carry high levels of flu germs during flu season, according to the 2018 Finnish study. Data collected by travel company Travelmath in 2015 found that water fountain buttons are also likely to carry germs of all kinds, as people sneeze or cough on their hands and then touch different surfaces. To protect yourself, Dr. Arthur says, "use a paper towel or tissue to open doors or push elevator buttons."

Shop samples are often pretty common in airport shops and duty-free areas: make-up testers, perfume bottles, and even food can be available to try. "Avoid these at all costs as they have been exposed to coughs, sneezes, and even possible touching," Dr. Arthur tells Bustle.

That means staying away from sample bottles and jars. If you do want to try before you buy, Dr. Kaiser recommends sanitizing afterwards. "Use an alcohol-based hand rub before eating, or any other activity where you may introduce your hands to your nose or mouth and potentially bring some of those droplets along with them," he tells Bustle.

Luggage trays are big culprits when it comes to flu germs, but other people's bags can also carry viruses and bacteria. "Be aware that purses, backpacks or other items may have been on the floor or another dirty area," Dr. Arthur tells Bustle. Don't touch other people's stuff at the airport; it's a good rule in general, but particularly important in flu season, as you really don't know where it's been or whether it might carry germs. If somebody in an airport café puts their purse on the table you want, wait for the surface to be disinfected before you sit down.

Self-help check-in kiosks can be serious life-savers at airports, but their screens and buttons can carry a hefty amount of flu germs, according to testing by an American insurance company released in 2018. Interactive screens used by thousands of passengers with bare fingers are, unsurprisingly, very likely to have flu germs on their surfaces. It's like your own smartphone touch screen, except with thousands of fingers.

It's a good idea to disinfect your own hands before and after you use check-in kiosks, particularly if you're ill yourself, but don't try to wipe them down yourself, as the airline will likely not appreciate it.

Communal playgrounds for children in airports can be crowded with children who are carrying the flu — and that can mean they're not exactly healthy. Kids in daycare and elementary school, Dr. Arthur tells Bustle, "are often sitting on the floor or playing with toys and other items that may not be clean." The same thing can happen at airport playgrounds.

It depends on the play area itself and how often it's cleaned, but with thousands of potentially-ill kids passing through every day, playgrounds at airports can be full of flu germs. Steer clear if you don't have kids yourself.

If you'd like to avoid flu germs this holiday season, it's a good idea to go to the airport armed with travel-sized hand sanitizer and wipes. Make sure you stay away from any passengers who are coughing or sneezing, and beware the luggage trays.

Studies cited:

Ikonen, N., Savolainen-Kopra, C., Enstone, J.E. et al. (2018) Deposition of respiratory virus pathogens on frequently touched surfaces at airports. BMC Infect Dis, 18, 437, doi:10.1186/s12879-018-3150-5

Experts:

Dr. Kristine Arthur M.D., internist at MemorialCare Medical Group

Dr. Scott Kaiser M.D., family physician with Providence Saint John's Health Center