How do you stop your safety glasses from fogging up?

Moist air will typically condense inside your glasses when they are at a lower temperature. Many manufacturers add an anti-fog coating to their safety glasses during the manufacturing process. If you are not lucky enough to purchase a pair with this coating, there are anti-fog sprays on the market that can do the same job. Also try Rain-X, vinegar, and even your own saliva will work to prevent your glasses from fogging up.