Exposure Limits

The link between the experience of disturbance and the dB(A) level, which has been analyzed in various studies, indicates that 40 dB(A) would be equivalent to a degree of disturbance immediately below “somewhat disturbing.” 1 Ьь н — suit indicates that the ventilation noise in offices should lie beneath this level. When assessing noise, however, it is necessary to take into account the fact that the reaction to disturbance is influenced by many noise characteristics other than the noise level, and also by working environment factors other than the noise environment. The tolerance to noise is also reduced when working on particularly challenging tasks.8 Under conditions of exposure and working sit­uations of this kind, the noise level should not exceed 35 dB(A). Concerning the dB(A) weighting of the ventilation noise, it should be pointed out that this alternative can exhibit a very poor correlation to the experience of disturbance by the noise in question.8 Previous analyses indicate, however, that the correla­tion of the А-weighting procedure is no poorer than that of other weightings, lor example dB(B), dB(C), or dB(D).8 The most reliable conclusions with re­spect to the negative influence of ventilation noise on exposure are obtained from an analysis of the actual symptoms of inconvenience.