Can the Sun Actually Disinfect Your Laundry?

Healthy Living

July 28, 2022

For hundreds of years, clotheslines have played an important role in people’s wash routines. These days, though, most people toss their dirty duds in the dryer instead of pinning them to the line. And that shift to better tech gives us cleaner, more sanitary clothes, right?

Maybe. But maybe not.

It turns out that hanging your linens on the line still offers some health benefits. That’s thanks to mother nature — and more specifically, the sun.

Laundry experts have long believed that time in the sun helps eradicate germs. As it turns out, that’s more than just an old wives’ tale. Sunlight really does have the ability to lower microbial loads.

Hanging your clothes out to dry can leave them crisp, fresh and sanitized. Here’s how to make the most of the sun’s power, even when you have a clothes dryer close at hand.

Sunlight’s Germ-killing Properties

Your mother might have told you that sunlight kills germs. Skeptical? Well, Mom’s instincts were correct. In fact, several studies support this commonly held belief in the power of the sun.

In one study, researchers compared socks that were contaminated with foot fungi. Half the socks stayed in the sun for three days while the other half sat inside. At the end of the experiment, fewer fungi remained on the sun-exposed socks than the indoor ones.

In another study, researchers used bottles of water that were contaminated with hepatitis A virus or murine Norovirus. Compared to heat and darkness, sunlight did a better job of inactivating the viruses.

Other research has shown that sunlight can kill both tuberculosis and E. coli bacteria.

Laundry on the Line

You toss your kitchen rags and dirty clothes in the washing machine with the assumption that they’ll get good and clean. While they may come out smelling fresh, the same microbes that went into the wash are likely coming right back out. 

Even worse, bacteria or virus particles that are on just one item could spread to the whole load.

The washing machine alone simply isn’t enough to kill microorganisms. Even using hot water won’t do the trick. Bleach can help, but not all loads are suitable for bleaching.

The key to getting rid of germs on fabric is found in the drying process. But line drying your clothes inside doesn’t do much good. You need either heat or sunlight. Cranking the dryer to the highest setting and letting the clothes tumble for half an hour or more knocks out most microorganisms.

Another option is to hang your items in the sun. 

Outdoors, the ultraviolet radiation (UV) from the sun’s rays can work its magic. UV disinfection is so effective that it’s sometimes used at water treatment plants. In other words? It works for drinking water, and it can work for your kitchen towels, too.

Keep in mind that most studies on germs and sunlight involve leaving items outdoors for several hours or more. For the most benefit, plan to leave your laundry on the line for a good long stretch.

By the end of that time, you may even find that your whites look a bit whiter. Sunlight is known to have a bleaching effect that helps lift dingy stains. Line drying can also reduce static cling and loosen wrinkles, so you may be able to get away with fewer chemical additives in your wash loads.

Freshening Tips for Large Household Items

The sun isn’t just a fresh alternative for drying wet laundry. You can also harness its power to disinfect items that won’t fit in the washing machine.

Take your mattress, for instance. It’s probably harboring all sorts of microorganisms. There’s no way you can stuff it in the washing machine, but you could take it outside to let the sun do its thing. Family Handyman suggests placing the mattress on a tarp in the backyard and letting it sit in the sun for three to six hours.

You can do the same with couch cushions. Their covers might be machine washable, but the inside cushions will certainly benefit from a day in the sun. (Of course, always consult the manufacturer’s care instructions before putting any components of your furniture in the washing machine — or outside, for that matter.)

Bed pillows can also be machine washed, but they may still benefit from a dose of sunlight as well. You can air your pillows without washing them or place them in the sun after a trip through the machine. The sun will provide disinfecting power, and the breeze will help fluff the pillows. Just be sure to get them thoroughly dry so they don’t become a breeding ground for mold and mildew.

Other household items that you can freshen with sunlight include throw rugs, duvets, luggage and stuffed animals.

Sunlight and Indoor Disinfection

UV radiation has typically received the credit for sunlight’s germ-killing abilities. That’s a key reason why line drying typically takes place outdoors. It turns out, though, that it may not be just the UV component of sunlight that takes care of germs.

Researchers tested this by letting dust sit undisturbed in tiny rooms with varying degrees of light for 90 days. At the end, the rooms that had been kept in the dark had the most microbe-ridden dust. The levels were much lower in the other two types of rooms.

Both of the other room categories had been exposed to light. The scientists flooded one set with UV rays. Those rooms ended up with about half as many germs as the dark rooms.

The other set of rooms was bathed in natural daylight that passed through window glass. Now, window glass is known for filtering out the majority of UV rays. Still, the daylight did an impressive job of reducing the microorganism levels. Those rooms had only slightly higher contamination levels than the UV-exposed rooms.

The takeaway from this experiment? Maybe open your window blinds more often. Letting sunlight pour through your windows is an easy way to keep your home fresh and clean.

But the sun won’t disinfect everything. Case in point? Lice.

One time when you shouldn’t rely on sunshine to get rid of unwanted visitors is when you’re dealing with head lice. You can’t count on the sun alone to get rid of those critters.

In one study, researchers tried getting rid of lice by washing pillowcases in cold water and then hanging them out to dry in the sun. It didn’t work well.

Instead, they found that heat was the best way to eradicate lice from fabric surfaces. The researchers had much better results when they washed the pillowcases in hot water and placed them in a hot clothes dryer for at least 15 minutes.

When it comes to lice, stick with the washer and dryer. For most other situations, you may get just as much germ-killing power from the clothesline as you would from the dryer. And as a bonus, hanging clothes on the line is much kinder to the planet than using the dryer’s high-heat setting.