Progress and recommendations of developing occupational exposure limits for noise-A systematic review

Noise exposure limit is one of the critical measures to prevent noise-induced hearing loss (NIHL). This review aimed to review the progress and recommendations for developing occupational exposure limits (OELs) for workplace noise.

A systematic review was used. Thirty-eight national or international organizations' noise exposure standards (including OEL) and laws, regulations, and guidelines for noise exposure control were analyzed. Articles on recommendations for revising noise OEL standards between 2000 and 2023 were selected.

The definition of different noise types (especially for non-steady and impulsive noise) varied worldwide, and the used 8-h OEL varied from 80 to 90 dB(A). Maximum sound pressure level (L_max) and noise dose for industrial noise and peak sound pressure level (L_peak) for impulsive noise have been incorporated into the OELs. Countries developed noise risk management measures based on OELs, action levels (ALs), and exposure risk ratio or classification. The risk of co-exposure to noise and ototoxic organic substances and the effects of noise on susceptible populations were concerns in EU country standards. Scholars suggested revising the existing noise exposure standards based on noise's temporal structure (expressed by kurtosis), effective noise level, impulsive noise OEL, action level, and key factors of risk assessment.

Indicators such as L_max, noise dose, L_peak, and action level can be incorporated into noise OELs. Developing noise OEL standards should consider the co-exposure of noise and ototoxic substances, HPD's noise attenuation, susceptible groups, and noise's temporal structure.