Annex 2 of NR15 – Tolerance Limits for Impact Noise

(SEPRT Ordinance No. 1359, December 9, 2019)

1. Impact noise is defined as noise that presents peaks of acoustic energy lasting less than one (1) second, at intervals greater than one (1) second.

2. Impact levels should be evaluated in decibels (dB) using a sound level meter operating on the linear circuit and impact response circuit. Readings should be taken close to the worker’s ear. The tolerance limit for impact noise is 130 dB (linear). In the intervals between peaks, the existing noise should be evaluated as continuous noise.

3. If a sound level meter with an impact response circuit is not available, readings taken with the fast response (FAST) circuit and “C” weighting circuit will be valid. In this case, the tolerance limit is 120 dB(C).

4. Activities or operations that expose workers, without adequate protection, to impact noise levels exceeding 140 dB (LINEAR), measured on the impact response circuit, or exceeding 130 dB(C), measured on the fast response (FAST) circuit, will pose a serious and imminent risk.