what seems to fog my glasses or goggles is the moisture from the skin on my face. I like a little breeze flowing around my safety glasses. they might fog if I stop moving, so that's where the strap comes in. I lower them off my face. in some cases, like brief stops to cross a road, I'll slide them forward toward the edge of my nose, they fog less when they are farther from my skin & when I get going they will clear more quickly. then I slide them back up onto the bridge of my nose