- Class I lasers are low powered, generally between 0.04 and 0.22 milliwatts (mW). They are exempt from any control measures. A laser may also be considered to be a Class I if a more powerful laser is contained within an enclosure. Embedded laser printers and CD players are good examples of this laser class.
- Class II lasers operate at less than 1 mW. The human eye blink reflex provides some protection but they can produce eye injuries if viewed for relatively long periods of time. These lasers require CAUTION labels warning not to stare at the beam. Bar code readers are a good example of this laser class.
- Class IIIa lasers operate at less than 5 mW. CAUTION labels warning to avoid direct beam viewing are required. Solid state laser pointers are an example of this class.
- Class IIIb lasers operate at less than 500 mW. They can cause eye and skin damage if exposed to the direct beam or through reflections. Control measures include area entry requirements, WARNING labels, and protective eye wear.
- Class IV lasers operate at more than500 mW. These lasers will produce eye damage and also are skin and fire hazards. Control measures include area entry requirements, WARNING labels, and protective eye wear.
- To the eye through corneal or retinal burns.
- Skin burns
- Chemical hazards from the contents of eximer, dye, and chemical lasers.Laser induced reactions can also release hazardous particulate and gaseous products.
- Electrical hazards from high-power laser systems.