The maximum permissible exposure (MPE) to laser radiation depends on which factors?

The maximum permissible exposure (MPE) to laser radiation is influenced by several factors that determine how safe an exposure level is for an individual. Duration of exposure is crucial, as longer exposure times generally increase the risk of injury from laser radiation. The pulse repetition frequency is also significant, particularly for pulsed lasers, as it can dictate how much energy is delivered over a specific period of time. Lastly, wavelength plays a critical role in the MPE because different wavelengths of laser light can have varying biological effects on human tissue, thus influencing the permissible exposure levels.

The combination of these three factors—duration of exposure, pulse repetition frequency, and wavelength—provides a comprehensive understanding of the risks associated with laser exposure, which is why this option accurately describes what influences MPE.