According to an industry study, you should be cleaning more than just the inside of this appliance.
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You may pat yourself on the back after using some elbow grease to scrub down your microwave. However, like many other appliances in your kitchen, you should also be cleaning the exterior. A study conducted by kitchen manufacturer Kimberly-Clark Professional shows just how filthy the exterior of a microwave—and especially the door handle—can be.

The study, which was authored a team of hygienists commissioned by Kimberly-Clark, found that microwave handles are one of the dirtiest surfaces to be touched on a daily basis in a kitchen. The study was conducted in an office setting, with professionals collecting "nearly 5,000 individual swabs from office buildings housing more than 3,000 employees," according to the published report.

You may be thinking, "Well, offices are dirtier than my home," but you should know that the team behind the study visited various offices, too—including law firms, insurance companies, and call centers. Each staff was different in size, but all were working in corporate offices where some form of a kitchen was available to them. All offices—regardless of size—had one thing in common: The average amount of germs living on microwave handles was alarming.

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Dr. Charles Gerba, a microbiology professor at the University of Arizona, was the study's lead author. His results showed that 48 percent of microwave door handles contained high levels of bacterial contamination, an industry standard of an ATP count of 300 or higher. ATP, known as Adenosine Triphosphate, is shown to signify a particularly troubling source of bacteria: "Everyday objects with an ATP reading of 300 of higher are considered to have a high risk for illness transmission."

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You won't be surprised to hear that other highly dirty objects mentioned in the study include sink faucet handles, refrigerator door handles, as well as buttons on appliances and water fountains. Basically, the study is a solid reminder that you need to be cleaning more than just the interior of appliances.

After all, would you clean just the inside of your oven and not the stovetop? Of course not! Take the time to keep your kitchen surfaces and appliances safe and clean with our ultimate guide to deep cleaning your kitchen.