Your lenses can steam up in humid conditions when the air is warm and moist. Air comes into contact with the cold surface of the lens causing the water held in the air as vapour, to condense into liquid droplets as it cools against the surface on your lens.
The amount of fogging you experience depends on environmental factors (e.g. air temperature, humidity and wind), the shape of your face and glasses, and what you are doing. You might find your glasses steam up when you are:
- Playing sport, jogging or cycling
- Going inside out of the cold
- Drinking a hot drink
- Working in a steamy kitchen
- Opening a dishwasher or oven door
Keeping your lenses fog free is not only a nuisance, but it by impairing your vision could pose a health and safety risk. Choose a lens with anti-fog coating, which causes water droplets to form an invisible film on the surface of the lens, rather than creating a fog.