When warm air hits a cool surface, condensation can form. Just remember how your glasses fog up when you walk into a warm building after being out in the cold. The same thing happens with a mask. When your warm breath escapes through the top of the mask, it hits the lenses of your glasses and causes them to fog up.
The American Academy of Ophthalmology (AAO) says one of the first things to check is how the mask is fitting to your face. If it is not fitted properly, there is a higher chance that warm air will seep through the top and into your eyes. The academy also recommends putting your glasses on after the mask. As an extra precaution, you can add a piece of adhesive or tape to seal the top shut.
Make sure your mask fits your face. An ill-fitting mask will allow warm air to escape from the top and fog up your lenses.
Push your glasses forward on your nose to allow more air to circulate, and keep your breath from fogging up the lenses..
Try pulling your mask up over your nose and rest your glasses on top of it to block the air from escaping and causing fogging. NOTE: If you try this method, make sure your mask still fits properly over your face to completely cover your nose and mouth.
Wipe your lenses with an anti-fogging solution or gently wash your lenses with soap and water before wearing them to help keep water droplets from building up and fogging your lenses.
NOTE: Some of these "hacks" work better than others. The "Soap and Water" hack that is all over the Internet. Its value is questionable and often depends on the type and quality of soap used. According to an article by The Royal College of Surgeons of England, washing your glasses with soapy water leaves behind a thin film that reduces surface tension and causes the water molecules to spread out evenly into a transparent layer, thus de-fogging your glasses or creating a fog barrier. The soap acts as a surfactant — which stands for surface active agent.
Instead of soap, apply shaving cream and wipe off.
Put a tissue inside the top of the mask: If you fold a tissue horizontally and put it between your face and the top of your mask—so it sits over the bridge of your nose— the moisture from your breath will be absorbed by the tissue instead of hitting your glasses lenses.
Squish a folded tissue between your mouth and the mask. It will absorb the warm, moist air and prevent your lenses from clouding up.
"Masks may be more effective as a “source control” because they can prevent larger expelled droplets from evaporating into smaller droplets that can travel farther."
(June 26, 2020) The University of California-San Francisco
If you are a mask manufacturer and want your face mask to be considered for publication on our website, please send a sample supply for review along with a press release. We'll then donate your masks to local organizations including medical personnel and front line workers. Only quality masks will be considered for review and highlighted on our website.