How long can bacteria live on surfaces

Chances are, you're feeling more cognizant of viruses lately. To avoid them, you might cover you hand with your sleeve to hold onto a subway pole. To not spread them, you may cough into your elbow instead of your hand.

But what happens to the viruses that make their way onto subway poles, your clothes, and doorknobs? Here's what you should know about how long viruses can live on various surfaces.

Lifespan depends on the virus and the surface

In light of the novel coronavirus, researchers are looking at how SARS-CoV-2 and other coronaviruses behave on surfaces.

A recent study from scientists at a federal laboratory reported that SARS-CoV-2— the virus causing the current coronavirus pandemic — can live on plastic and stainless steel surfaces for up to 72 hours, on cardboard for up to 24 hours, and on copper for 4 hours. This was how long the virus could survive in large enough amounts to be transmissible, according to the researchers. 

Another 2020 study published in the Journal of Hospital Infection analyzed 22 studies on other SARS and MERS coronaviruses. Researchers found that, on average, the viruses persisted on metal, plastic, and glass surfaces at room temperature for four to five days, and could persist for up to nine days depending on temperature and humidity.

Therefore, how long harmful germs live on different surfaces is "very specific to the pathogen, environmental factors like humidity, and also what surface it's on," says Todd Nega, MD, an infectious disease specialist at NorthShore University HealthSystem.

With fabrics, it's unclear how long viruses can last. But generally, they tend to last for a shorter amount of time on fabric compared to hard surfaces like stainless steel, according to the Mayo Clinic. It may also depend on what material the fabric is made from.

For a 2015 study in the Polish journal Medycyna Pracy, researchers looked at fabrics in industrial facilities, stables, homes, and a zoo. They didn't study viruses but they did see a correlation between how much fungi and bacteria contaminated the fabric depending on its material. They reported that smoother fibers — synthetic, semi-synthetic, and silk fibers — showed less microbial contamination than natural fibers like wool, hemp, or cotton.

This matters because you come in contact with fabric throughout your day. There are the clothes you wear, the towel you dry off with after a shower, the sheets you sleep on. "This is why we're very careful with contact isolation in hospital," Nega says. "In healthcare, we look at not contaminating things versus decontaminating them."

As an extra precaution, some experts recommend changing into clean clothes when you get home if you've been in contact with large groups of people at work throughout the day.

How to clean hard surfaces

For hard surfaces like tabletops, doorknobs, countertops, sinks, and glass, the CDC recommends using alcohol-based disinfecting wipes or solutions that are at least 70% alcohol, diluted bleach solutions, or other disinfecting products registered by the US Environmental Protection Agency (EPA). 

First, make sure to protect your skin by wearing gloves. And then check that you're using enough of the cleaning solution to properly disinfect the surface.

For example, if you're using Chlorox Disinfecting Wipes, there should be enough solution on the wipe to leave the surface visibly wet for at least four minutes while air-drying. If it's not visibly wet for four minutes, it could mean you've been overly ambitious and cleaned too much surface area with the wipe already.

Here's a complete list of EPA-registered disinfectants and also a list of disinfectants the EPA specifically recommends for disinfecting surfaces against SARS-CoV-2.

How to clean fabrics

One of the best things you can do to reduce your exposure to viruses, and other germs, is to wash your clothes and other fabrics regularly. Washing clothes in water of at least 86 degrees Fahrenheit "significantly decreases, but does not eliminate, the bacterial burden," according to a study published in 2020 in the Journal of Small Animal Practice that examined bacteria on clinicians' scrubs.

To further sanitize fabrics, add bleach or color-safe bleach diluted with water. But first check your fabric's care instructions to make sure you're using it correctly. Be careful not to over-fill the washing machine. This gives the clothes room to vigorously stir in the disinfecting, soapy water, according to the American Chemistry Council's Water Quality and Health Council.

Running clothes through a drying cycle is key to eliminating germs, too. The high-heat setting is most effective, but again — check the specific instructions on your fabric to avoid damaging the fabric. You can also hang clothes to dry outside in direct sunlight. According to one study, the sun's ultraviolet light has disinfecting properties that kills certain types of bacteria.

If someone in your home has been sick, make sure to sanitize your laundry basket or hamper, as well as the washing machine itself. Check your specific washer for instructions or a clean-out cycle. And after all that cleaning — don't forget to wash your own hands, too.

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