Which class of lasers are potentially hazardous under any viewing conditions and may present skin hazards if focused and stable?

• A. Class 4
• B. Class 3R
• C. Class 3B
• D. Class 2

Answer: (C)

Understanding how laser safety classes map to potential harm helps explain why this option is correct. A Class 3B laser emits enough energy that direct exposure to the eyes can cause injury, and it can also damage skin if the beam is concentrated and held steady on a small area long enough to burn. That combination—eye harm from direct viewing and skin injury from a focused, stable beam—fits the description given. It signals a level of hazard that requires strict controls, not casual handling.

In contrast, other classes have different risk profiles. Class 2 is generally eye-safe under normal viewing because of the aversion response (blink/reflex) to a bright visible beam. Class 3R is hazardous mainly if the beam is viewed directly, but it’s not typically associated with skin burns. Class 4 presents even broader and more severe hazards, including potential fire risk and higher tissue damage.