This is the peak level of the sound pressure wave with no time constant applied. For Noise at Work measurements the Peak level should be C weighted (check the sound level meter specifications to ensure this is the case).
Important Note: Do not confuse the Peak Level (LPeak) with the Max Level (LMax). The Max level is the maximum RMS sound level with a time constant applied (Fast or Slow) and is very different to the Peak.
In the Noise at Work Regulations 1989, action must be taken when the Peak level gets to 140 dB(C).
For the new regulations, Directive 2003/10/EC specifies three Peak action levels: