Sunlight as a Disinfectant for Laundry

Dear Home-Ec 101,
I’ve seen a couple of posts where you’ve mentioned that sunlight is a disinfectant… I wondered if you had any idea how effective it actually is, and whether the temperature outside influences its effectiveness? I hang my laundry outside to dry whenever possible (generally when it’s above freezing) but a recent cold/flu epidemic in our household has me wondering if I should be doing more to get rid of germs in my laundry than just hot water washes and sunlight.
Thanks for your thoughts!
Sincerely,
Sunny days taking my cares away

Heather says:

You pose an outstanding question and I wish I had a good answer, backed up with strong data, for you, but the sad truth is I don’t.

There are so many variables involved with hanging clothes outside in the sun to dry that don’t really translate well to laboratory testing.

Think about it, off the top of my head here’s what came to mind:

• What latitude? The equator is significantly different than Norway
• Direct / indirect sunlight
• Ambient temperature
• Humidity
• Relative cleanliness of the clothing hung outside
• Thickness of the fabric

So I began researching. Had I really been using an old wives tale as a resource here on Home-Ec 101? (You really don’t want a peek inside my head, it’s quite cluttered in there and filled with second and third guessing)

The truth is that the UV from the sun does kill bacteria quite effectively.

From Penn State:

Microbes are uniquely vulnerable to the effects of light at wavelengths at or near 2537 Angstroms due to the resonance of this wavelength with molecular structures.

However, so does heat and generally drier conditions.

So what does this mean?

Sunlight is a disinfectant. Remember though that the term disinfectant only means:

an agent that frees from infection; especially : a chemical that destroys vegetative forms of harmful microorganisms (as bacteria and fungi) especially on inanimate objects but that may be less effective in destroying spores [credit: Merriam-Webster]

Sunlight will reduce the overall amount of bacteria living on your fabrics, but it won’t sterilize them. (Remember, we’ve talked about the difference between clean, sanitary, and sterile before). So, yes, if you have a contagious bug making the rounds in your home, go ahead and hang the sheets and towels in the sun, after washing them properly, the fresh air certainly won’t do you any harm, either. (Apply sunscreen, yada yada yada).

Unless you have people still in the chewing on fabric phase -or have a houseful of pinkeye the relative cleanliness of your laundry isn’t a huge deal – do take care with your kitchen laundry, of course.

If however, you have someone in the house with severe allergies, know that the collection of pollen on their pillowcases is probably going to make them absolutely miserable and it’s not worth the extra effort.

I hope everyone is feeling better.

Submit your questions to helpme@home-ec101.com.