In airsoft, eye protection is of paramount importance. An airsoft pellet can do devastating damage to an unprotected eye. However, eye protection can sometimes be a nuisance when the goggles fog up. It's a potentially dangerous condition because if you lift your goggles during play, you risk being hit in the eyes. However, by following a few steps, you can limit or eliminate fogging in your protective goggles.
Purchase top-quality protective goggles made for the sports of airsoft or paintball. These goggles are designed to provide the best protection against the impacts of pellets, but also are typically treated to inhibit fogging and may be available with dual-pane "thermal" lenses.
Use anti-fog spray or gel to treat the inside of the goggles unless the goggle instructions direct otherwise. Instructions for these products may vary, but typically you apply the spray or gel to the inside of the lens, let it dry, and then buff the lens clean with a non-scratching microfiber cloth. It is very important to make sure that the goggle instructions do not state that this will damage your lens.
Wear a sweatband or a do-rag on your forehead to help absorb sweat. The more that you get inside the goggles' protective space, the more likely that it will condense and cause fogging problems. A sweatband and taking the time between games to wipe your face free of sweat reduces that possibility.
If wearing a face mask, breathe downward. Direct your breath down under the front of the mask. Your breath is laden with moisture and heat, and when it gets trapped inside your goggles (especially with sweat), then fogging is very likely.
When buying goggles, test them for fit and comfort. The better they fit, the fewer the issues with airflow. If you do have a problem with fog, one way to help dissipate it is to "fan" the goggles. Grab an edge and quickly pull it away from your face just a fraction of an inch and then put it back, repeating the motion quickly. This "pumps" the humid air out of your goggles. Only do this if you know that you are not in danger of being shot!
Your vision is irreplaceable, so if you cannot see during a game let a referee or other players know immediately. Never remove your goggles during play.