Hi Mr Brightside
The levels you mention would not be that unusual for processes which produce percussive noise and it is unclear what level of attentuation you expect any hearing protection to afford.
Assuming you are in Great Btitain, the relevant standards to consider are set out in Regulation 4 of the Control of Noise at Work Regulations 2005, viz:
Exposure limit values and action values
4.—(1) The lower exposure action values are—
(a)a daily or weekly personal noise exposure of 80 dB (A-weighted); and
(b)a peak sound pressure of 135 dB (C-weighted).
(2) The upper exposure action values are—
(a)a daily or weekly personal noise exposure of 85 dB (A-weighted); and
(b)a peak sound pressure of 137 dB (C-weighted).
(3) The exposure limit values are—
(a)a daily or weekly personal noise exposure of 87 dB (A-weighted); and
(b)a peak sound pressure of 140 dB (C-weighted).
(4) Where the exposure of an employee to noise varies markedly from day to day, an employer may use weekly personal noise exposure in place of daily personal noise exposure for the purpose of compliance with these Regulations.
(5) In applying the exposure limit values in paragraph (3), but not in applying the lower and upper exposure action values in paragraphs (1) and (2), account shall be taken of the protection given to the employee by any personal hearing protectors provided by the employer in accordance with regulation 7(2).
I've highlighted one word in bold italics as these Regulations are relatively rare in that they do take account of PPE in terms of judging performance against a legislative numeric standard.
So, in terms of the peak, what you quote is substantially below the peak action level as measured in dB(C), so that your atttention should perhaps focus on where you are in terms of overall exposure in dB(A) which of course takes account of the noise when it is loudest and the periods when it is not so loud.
Unless your processes are very unusual I would expect that you could find hearing protectors for most, if not all, of those involved that would bring their exposure down below the lower exposure action level without the doubling up that you are considering.
The original noise at work regulations were made in 1987 with slightly less stringent limits, but if there was no difficulty in finding hearing protectors to provide adequate protection against processes producing percussive noise then [and before the Regulations came into effect when we worked to a non statutory Department of Employment Code of Practice], there should be little difficulty now.
Good luck, Peter