During cold and flu season, sickness is commonly spread through coughing, sneezing and even touching surfaces. One of these surfaces that germs can live on: your clothing.
“Your clothing is porous and therefore is essentially a solid petri dish,” said microbiologist Jason Tetro, also known as “The Germ Guy” and author of “The Germ Code” and “The Germ Files.” “Anything that comes into contact with your clothes is going to stick to [them].”
But how long do germs stay on your clothing, and how likely is it that they’ll infect you? We talked to experts about which germs tend to live on clothing the longest, the types of fabric that harbour germs and how to properly wash your clothes.
Clothes can pick up germs from being in contact with contaminated surfaces or even just from the air, Tetro explained.
If you add moisture or humidity to the clothing (like if you’re sweating, for example), the germs may get stuck within the fibers. Because most of these pathogens get trapped in the fabric, you are not likely to get sick just from touching your clothes.
“There has to be some kind of shaking of the fabric to release them into the air so that you can get exposed,” Tetro explained.
If the fabric is dry, it’s also not that much of a risk because the germs will likely stay on the fabric.
“If the fabric is a little bit wet … or humid [like from sweat], then [pathogens] could potentially end up on your fingers, and then you can expose yourself through [touching] your nose and your mouth,” he said.
Some germs live on clothing and surfaces longer than others.
“Depending on the conditions, bacteria and fungi can stay viable in the fabrics for quite a long time and up to 90 days,” Tetro said. “Viruses, however, [live for] significantly less time.”
That said, when it comes to actually getting sick from harmful germs, there has to be a high enough dose, known as the minimal infective dose, for you to get infected.
The minimal infective dose for common respiratory viruses, like flu, COVID and RSV, is usually 8 to 12 hours, he said.
“For most of the respiratory viruses, clothing is not a major source of transmission,” added Dr. Anne Liu, an infectious diseases physician and allergist at Stanford Medicine. “Direct exchange of respiratory particles through sneezing and coughing into air … is by far the more common way of spreading these germs.”
However, you are more likely to pick up norovirus, also commonly known as the “stomach bug,” from surfaces, including clothing.
“Norovirus … [can] survive an entire month in pretty much any condition,” Tetro said.
It’s highly contagious, and it only takes a few particles for you to get sick, according to the Centers for Disease Control and Prevention.
“Surface contamination is a major route of transmission to others,” Liu said. “[And] unlike respiratory viruses, norovirus cannot be killed by alcohol-based hand sanitisers or cleaners.”
The type of fabric can also affect how long germs will live on your clothing.
“Synthetic materials, such as polyester, permit survival of viruses longer than natural fibers like cotton and wool,” Liu said.
So why does that happen?
“Synthetic fabrics are usually made from petrochemicals, which means they’re very oily,” Tetro added. “The microbes, which also are very oily on the outside … tend to stick around much longer … and they end up growing at a much faster rate.”
“I don’t want people to panic … [and think they have] to go through this elaborate laundry routine,” said Patric Richardson, known as The Laundry Evangelist.
If you’re washing your clothes in detergent and putting them in the dryer, that is already doing a lot.
“Norovirus and the respiratory viruses are killed by detergents,” Liu said. “For the respiratory viruses, expending a lot of time and energy on doing laundry is not high-yield.”
That said, if you are sick or around someone who is (especially with norovirus), there are some easy steps you can take to disinfect your clothes.
“Hot is your best friend against microbes,” Tetro said. Microbes generally die at temperatures that are at least 140 degrees Fahrenheit.
Washing your clothes in the hottest water they can handle and drying on the highest setting can help disinfect them.
Tetro suggests using a laundry detergent that contains enzymes called lipases.
“The enzymes are … going to break down the microbes,” he explained.
Richardson recommends adding oxygen bleach in addition to detergent. This is safe to use on colours and most fabrics (just not wool or silk).
“When you mix it with water, you’re creating hydrogen peroxide,” Richardson explained. “That’s very sterile.”
Because the tub of your washer can also get contaminated with microbes, Tetro advises running an empty hot-water cycle with bleach about once a month to clean it.
“Ironing and/or steaming can often get the clothes hot enough to sterilise them,” Richardson said.
You should check the brand to make sure your iron or steamer gets hot enough to disinfect. This can be particularly helpful for suits or jackets.
Also, if you have a steam setting on your dryer, this can be effective to sanitise pillows, stuffies or other items. (He recommends starting the steam a couple of minutes before you throw the items in and then letting them run for a couple of minutes.)
Richardson said that although he usually does his laundry once a week, when he is sick, he is more diligent about washing his clothes promptly.
“If you are sick, you should put those clothes away when you are better and wash them as soon as you can,” Tetro said. “This includes scarfs, hats and mitts, [especially] if you were wiping away those sniffles.”
When you are sick or around someone who is sick, don’t forget to do what we learned in 2020: wear a mask, wash your hands and clean high-touch hard surfaces, such as door knobs.
Liu said these are some of the most effective ways to avoid getting sick.
