Eye and face protection (29 CFR 1910.133): Safety glasses are recommended at all times in the laboratory and required when working with potentially hazardous chemicals, infectious materials or high energy beta emitting radiation (32P). Chemical splash goggles or face shield with safety glasses must be worn when working with hazardous chemicals in quantities of 1 liter or more or when working with systems under positive or negative pressure. A UV resistant face shield is required when working with transillumators. A face shield must be worn when working with liquid nitrogen. All safety eyewear must meet ANSI Z87-2003. Face shields should never be worn alone--wear safety glasses or chemical splash goggles as well.