Estimate HSE daily or weekly personal noise exposure from measured A-weighted exposure periods.
HSE Daily and Weekly Noise Exposure Formulas
For multiple periods in one day, HSE defines daily personal noise exposure as LEP,d = 10 log10[(1/T0) Σ(Ti × 10^(0.1 Li))], where T0 is 8 hours. Weekly personal exposure is LEP,w = 10 log10[(1/5) Σ 10^(0.1 LEP,d,i)].
The lower action value is 80 dB(A), the upper action value is 85 dB(A), and the exposure limit value is 87 dB(A). Action-value comparisons do not allow for hearing protection. The 87 dB(A) limit does take protection into account, so an unprotected calculation cannot establish limit-value compliance. Peak noise is assessed separately at 135, 137, and 140 dB(C).
Use and Limitations
Use measured or defensible task-based LAeq,T values. Weekly averaging is appropriate only where exposure varies markedly between working days. This screening tool does not replace a suitable and sufficient risk assessment by a competent person.
Primary references: HSE L108, Controlling Noise at Work, HSE action and limit values, and HSE exposure calculators.
