How to wear a face mask and not fog glasses

When you leave the house wearing a face mask while also wearing glasses, you may notice your breath sometimes flows upward and fogs them up.

It's a common occurrence for many people, and a number of factors can cause it: from the weather to the quality and fit of your mask. Luckily, there are a few ways you can prevent your glasses from fogging up while wearing a face mask.

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Your breath flowing upward could be a sign that your mask isn't tight enough around the bridge of your nose. If you're wearing a mask that has a metal band on the top, adjust it so it contours with your face.

If you're wearing a cloth mask that's adjustable, try tightening it, said Dr. Richard Martinello, professor of infectious diseases at Yale School of Medicine in New Haven, Connecticut.

With medical masks, like N95s, there should be little to no breath escaping, but the for regular, cloth masks that the public has been advised to wear, some fogging up is "normal," Martinello told TODAY.

You can also lower where the mask sits on your face "so your exhale breath exhaust is a little bit lower," Martinello said. But don't bring it down too much because the mask should cover a majority of your nose and all of your mouth.

You can also try to raise your glasses before you leave the house. Just avoid touching your face once out in public.

A lot of breath escaping and fogging up your glasses might mean that your mask doesn't allow adequate airflow, Joel Burken, Ph.D, chair of the department of civil, architectural and environment engineering at Missouri University of Science and Technology, told TODAY.

If you're using a filter, try one that allows more air to flow through. Burken's preliminary research has found that HEPA filters work best. If your mask is homemade and you can remove a layer of fabric from it, try that.

You can also make a mask with a different material.

To check if it's thick enough, hold it up to the light. If you can see individual fibers in the fabric, then it's probably not a good material, Dr. Scott Segal, an anesthesiologist at Wake Forest Baptist Health in Winston-Salem, North Carolina, who's been researching masks, told TODAY.

NBC's Vicky Nguyen reported that you can wash your glasses in soap and water. Letting them air-dry can prevent fogging because it leaves a protective film on the lenses. She also said you can buy a commercial anti-fogging spray.

Other hacks for preventing glasses from fogging up include spitting on them or rubbing on other substances that leave residue, like toothpaste and shaving cream.

Martinello discouraged spitting your glasses due to the coronavirus outbreak and stressed that you shouldn't do anything that can wet your mask.

"We know the moisture affects how well the filter material filters," he said.

Maura Hohman is the senior health editor for TODAY.com and has been covering health and wellness news and trends since 2015, when she graduated from journalism school. Her byline has appeared on TODAY, NBC News, US News & World Report, People, Everyday Health, WhatToExpect.com, History.com and more. Her interests include women's health, racial health disparities, mental health and COVID-19.