Appropriate eye protection is defined by the American National Standards Institute (ANSI) Z-87.1 standard. The standard describes both the design and performance criteria for various devices and the type of device to be used for particular operations (five different types of hazards).

Most chemical companies require that workers in laboratories wear industrial standard safety glasses (plain or prescription) with side shields as minimum protection. Some require side shields that are either permanently attached. A few do not permit frames of conducting material (metal).

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As the nature and degree of the hazard increases, the amount of protection used should also increase. Chemical splash safety goggles should be worn when (1) handling chemicals or biologicals known to be hazardous to the eyes, (2) using chemicals or biologicals which you don’t know if they are hazardous to the eyes, and (3) working with liquids which are hotter than 60°C. Note that safety goggles of the “impact type” (directly ventilated) are not suitable for chemical splash protection. Impact safety goggles are intended to provide greater protection from solid particles than safety glasses.

Sometimes making the distinction between safety glasses and safety goggles can be difficult. Remember, the safety goggle seals to the face or fits the face snuggly. If you can stick your finger between the device and your face, it is not a safety goggle. It might even be safety glasses with a strap (headband temple as ANSI calls it).

If the chemical, biological or operation may injure the face, mouth or neck, a face shield should be worn. According to the ANSI standard, face shields are to be used in addition to chemical splash goggles.

Source: Kaufman, James A., Laboratory Safety Guidelines - Expanded Edition, The Laboratory Safety Institute, www.labsafetyinstitute.org .