Our cellphones and laptops go everywhere with us — on the subway, to the grocery store, to work, even to the bathroom. Because touching shared surfaces is a surefire way to encounter a variety of microbes, how worried should you be about getting sick from your phone or laptop?

No more worried than you would be about getting sick from touching your other personal objects, says Jonathan Eisen, a microbiologist and professor at the University of California at Davis. An object such as a subway handrail or computer keyboard can harbor microbes including pathogens — infectious organisms that cause disease — but those pathogens can make you sick only in the right environment and with the right transmission method.

If you’re the only person using your laptop and phone, and you use them in a normal, everyday environment such as your house or workplace, and you wash your hands and clean your devices regularly, you probably don’t need to be concerned; you’re basically sharing microbes with yourself, he says.

The risk increases when you’re actively transferring harmful microbes into your body or coming into contact with other people. For example, if you’re using a recipe on your computer and going back and forth between your keyboard and handling raw meat. In this case, you could be transferring a harmful microbe, such as E. coli or salmonella, onto the keyboard. In that case, it’s a good idea to wipe your keyboard down and wash your hands.

If someone sneezes on your phone and you touch it and then your mouth, you could get sick, but only because you touched your mouth. Using a keyboard in a public library or scrolling through your phone on the subway with the same hand you used to touch the railing would be riskier, because you’re exposing yourself to other peoples’ microbes, Eisen says. If you’re using your phone in a subway car, “it’s going to pick up a few microbes from the environment.” Somebody on the car might be sick, and “you don’t really necessarily want to sample all the microbes from everybody who has been in that subway car.”

But haven’t we been told that our phones are dirtier than a toilet seat? Maybe, but many studies that measure the presence of microbes on our devices (“swab tests”) fail to provide context for consumers, Eisen said. “Maybe it tells you something about how recently something was cleaned or how much food there is for the microbes in that particular environment, but it doesn’t tell you anything about the health risk.”

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Both helpful and harmful microbes exist everywhere, and trying to eliminate all microbes from an environment isn’t possible; you’d have to live in a bubble, he said. “This is not about eliminating risk, it’s about reducing risk,” Eisen added.

It’s more useful to consider the environment you’re in and how the microbes are transmitted. “Many nasty microbes, even though you can find them in the environment,” will not be transmitted and cause disease just by their mere presence on an object such as your keyboard.

There hasn’t been a lot of research into disease transmission from personal devices, but a recent study found no evidence that keyboards transmit disease, even in places that harbor lots of nasty microbes, such as hospitals. A 2019 paper that examined contamination on keyboards in health-care settings found that the majority of devices contained many microbes, including some pathogens, but researchers couldn’t find evidence of an impact on patients and workers.

“They did not disprove that there was an impact, there’s just no evidence of an impact,” Eisen says. The study’s authors noted that the issue is worthy of further research.

Instead of trying to eliminate all the microbes on your device with harsh cleaning agents, Eisen recommends using common sense to consider transmission methods — think about how many hands touch the handrail on a Metro escalator — and washing your hands often to avoid getting sick.

“Washing your hands is so effective because generally it’s your hands that are bringing things into your body,” he says. You don’t need to sanitize your phone with a UV light, but he recommends wiping it down often with water or a device-cleaning wipe. If you can’t get to a sink to wash your hands, use hand sanitizer. If your immune system is compromised or you’re regularly hanging out in an environment with harmful microbes, he recommends being even more vigilant.

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Brian Sansoni of the American Cleaning Institute suggests using a microfiber cloth to give your phone a gentle wipe-down when you notice smears and smudges. He wipes his screen — and phone case — daily and uses premoistened device-cleaning cloths, which he buys at electronics stores. Clean cases with a disinfecting wipe and wait for them to dry completely before putting them back on your device.

Melissa Maker, founder of boutique cleaning firm Clean My Space in Toronto, dispenses cleaning tips and advice on her YouTube channel, which includes a video on how to clean your laptop. Maker, who wipes her tablet with a microfiber cloth about three times a week, says the cleaning is more for device maintenance than killing bacteria.

Apple and Microsoft suggest powering off and unplugging devices before cleaning them, especially when using liquids. Liquid damage could void your device’s warranty, Maker says, so never spray anything directly onto the device and keep cleaning agents away from openings where liquid could seep in, such as charger or USB ports. Never use harsh cleaning agents such as bleach or ammonia — and definitely don’t use a window-cleaning product such as Windex, Maker says.

To clean screens, touch pads and exteriors, move a flat-weave microfiber cloth in an S pattern, starting from the top corner and zigzagging down to the bottom of the screen to avoid streaks and to cover larger areas, Maker says. A dry cloth should be enough to get rid of most fingerprints and smudges. You can moisten the cloth with a little water or a mix of water and mild soap. Put your index finger in the cloth and buff spots away using a circular motion. A little isopropyl alcohol (Maker uses 70 percent), which dries on contact, lifts away stubborn stains, such as adhesive residue or coffee spots.

To clean keyboards, gently wipe the keyboard with the cloth. Use compressed air and a soft-bristle toothbrush or cotton swab to free large particles such as dust or crumbs from between the keys. “Use short blasts and use the straw nozzle to direct the air,” she says, and hold the can about three inches away from the keyboard. You can also go over each key with some isopropyl alcohol on a swab.