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There are more than 320 million cell phones being used in America and according to Nielsen, about 50 percent are smartphones used heavily throughout the day.

But what if the portal to your work, entertainment, and social life could make you sick this flu season?

During this time of year, the flu is everywhere, including cell phones. There is a much greater chance of catching the flu via airborne transmission, but doctors say people should take precautions, including washing their hands and properly cleaning their mobile devices.

"Cellphones are 10 times as dirty as a toilet seat," Chuck Gerba, a professor of microbiology at the University of Arizona, told ABC News.

Cellphone users are faced with a conundrum. If you want to clean yours, wiping it with a damp terry cloth will not eliminate germs, bacteria, or viruses. And most manufacturers do not recommend using anything stronger - solvents, household cleaners, or alcohol-based solutions. People often don't clean their phones very thoroughly, even though the little gadgets follow them around offices, gyms, bathrooms, and eventually into their beds.

AT&T has recommended using a hands-free device, which will minimize your phone-to-face exposure. While they're at it, they advise their customers not to use their cellphones in the bathroom. 11mark, an integrated marketing agency, surveyed 1,000 Americans last year and found that 75 percent of respondents admitted to using their smartphones while on the toilet; it's grimy and, sometimes, rude.

To clean a phone, some people apply a small amount of alcohol-based cleaner to a cloth before wiping down their phones. This method has been shown to be the most effective for removing germs, though it can harm a phone's finish. Many companies, like S.C. Johnson, have begun to offer products specifically designed to clean and sanitize electronics.

But bugs like the flu are not often carried on your phone. Instead, the problem is germs on your hands from other people. In one experiment, Gerba placed the flu virus on an intern's door handle in an office building to see how quickly it would spread.

"If you don't share a cellphone you don't have to worry because it's only your germs," said Gerba. "But if one person has the flu virus on their hands, it will be on the hands of 40 percent of the other people in the office within four hours."

Doctors highlight the importance of washing your hands properly with either soap and water or an alcohol-based sanitizer before touching your phone or other high-traffic surfaces. Keep in mind, the average adult touches their face 16 times per hour.

With a little caution, you can ensure a squeaky-clean phone and a reduced risk of illness.