As soon as you strap on your cloth face mask and head out the door, your glasses fog up.

Why Does it Happen?

The science behind why our glasses fog when we wear a mask is fairly simple. As we wear our masks, warm breath escapes from the top of the mask and lands on the cooler lenses of our glasses. When that happens, it creates condensation, or fog. You might've noticed a similar effect when wearing glasses with a scarf or baclava in the winter, or when opening a hot oven door.

How to Stop Your Glasses from Fogging?

There’s a simple fix for fogged glasses, and it'll only take a minute or two. All you need is soap and water.

This advice comes from the medical journal Annals of the Royal College of Surgeons of England, courtesy of two doctors. And if their defogging trick can work in the emergency room, it can certainly work in the grocery store.

Your specs fog up because the mask directs your breath upward instead of in front of you, which is good for preventing disease transmission but bad for anyone with less-than-stellar eyesight.

Soap and water act like a cloak that reduces surface tension on the lenses. This magic mix allows the water molecules from your breath to distribute evenly, rather than cluster on your lens in a way that makes it difficult to see.

Here’s what to do:

• Always wash your hands with soap and water first: Remember, scrub for 20 seconds (two rounds of "Happy Birthday") before you rinse.

• Wet your glasses, then lather some soap on the lenses: There's no time limit for lens scrubbing, so be gentle and thorough.

• Rinse your glasses under warm water: Don't leave any soap suds on your lens -- if the fog didn't obstruct your vision, bubbles certainly will. They're not fun to rinse out of your eyes, either.

• Gently dry your glasses with a clean towel or lens cloth: Avoid using a towel that may scratch your delicate lenses.