1) The Annals of the Royal College of Surgeons of England published an article in 2011 that offered a simple method to prevent fogging, suggesting that, just before wearing a face mask, people wash their spectacles with soapy water, shake off the excess and then allow the lenses to air-dry.
“Washing the spectacles with soapy water leaves behind a thin surfactant film that reduces this surface tension and causes the water molecules to spread out evenly into a transparent layer,” the article reveals.
2) Another tactic is to consider the fit of your face mask, to prevent your exhaled breath from reaching your glasses. An easy hack is to place a folded tissue between your mouth and the mask. The tissue will absorb the warm, moist air, preventing it from reaching your glasses.
3) If you are using a surgical mask with ties, a 2014 article in the same journal advises going against your instincts. Tie the mask crisscross so that the top ties come below your ears and the bottom ties go above. It will make for a tighter fit.