123. (1) For the purposes of this Chapter, the exposure limit values and exposure action values in respect of the daily noise exposure levels and peak sound pressure are as follows:

(a) exposure limit values—

L_EX,8h = 87 dB(A) and p_peak = 140dB(C) in relation to 20 μPa;

(b) upper exposure action values—

L_EX,8h = 85 dB(A) and p_peak = 137dB(C) in relation to 20 μPa;

(c) lower exposure action values—

L_EX,8h = 80 dB(A) and p_peak = 135dB(C) in relation to 20 μPa.

(2) An employer, when applying the exposure limit values referred to in paragraph (1)(a) in determining an employee’s effective exposure, shall take account of the attenuation provided by individual hearing protectors worn by the employee.

(3) The exposure action values referred to in paragraphs (1)(b) and (c) apply irrespective of the attenuating effect of any such hearing protectors as referred to in paragraph (2).

(4) For activities where the daily noise exposure varies markedly from one working day to the next, an employer, for the purposes of applying the exposure limit values and the exposure action values, may use the weekly noise exposure level in place of the daily noise exposure level to assess the levels of noise to which the employer's employees are exposed, provided that—

(a) the weekly noise exposure level as shown by adequate monitoring does not exceed the exposure limit value of 87db(A), and

(b) appropriate measures are taken in order to reduce the risk associated with these activities to a minimum.