The instantaneous energy level of a pulsed laser can ionize things, making them more susceptible to combustion. Indeed, there are different rules for the safety

The instantaneous energy level of a pulsed laser can ionize things, making them more susceptible to combustion. Indeed, there are different rules for the safety ratings of pulsed and continuous wave (CW) lasers at equal average power. An analogy is a spark plug in an engine -- it produces relatively little average energy, but the instantaneous intensity is quite high.