The reason why your glasses fog up when you wear a face covering is because warm air from inside the mask escapes through openings at the top (near your cheeks and nose) and clashes with the cooler air on your glasses, causing condensation to build up on your lenses. The process is similar to when eyeglass-wearers experience foggy lenses when they go from inside to outside during cold weather conditions. Luckily, there are a few easy solutions to your fogging problem that’ll keep you seeing clearly and safely for as long as masks are recommended.