LEX,8h noise exposure

How do you use the tool?

Enter one or more shifts, each with its own LAeq and duration Te, plus the peak level L_Cpeak. The tool computes the worker’s daily personal noise exposure level LEX,8h and returns the band relative to the action values and the limit value of Italian D.Lgs 81/08 Title VIII Chapter II, with the related preventive measures set by the law.

Computation of a worker’s daily personal noise exposure level L_EX,8h, from one or more exposure periods with distinct levels and durations. It returns the band relative to the action values and the limit value of Italian D.Lgs 81/08 Title VIII Chapter II, with the related preventive measures set by the law.

How is LEX,8h computed?

The level referenced to 8 hours is LEX,8h = 10·log₁₀[(1/T₀)·Σ Te,i·10^(LAeq,i/10)], with a fixed divisor T₀ = 8 h, not the sum of the durations. Cumulative exposures over 8 h give a LEX,8h higher than the mean LAeq, under 8 h lower. The peak L_Cpeak is assessed on the worst shift, not averaged.

Daily personal exposure level, referenced to 8 hours:

$$L_{EX,8h}=10{\log }_{10}\left[\frac{1}{T_0}\sum _i{T}_{e,i}10^{L_{Aeq,i}/10}\right][\mathrm{dB}(\mathrm{A})]$$

T₀      = 8 hours (reference duration)
LAeq,i  = A-weighted equivalent level of period i
Te,i    = duration of period i [hours]

The divisor is T₀ = 8, not the sum of the Te,i. Cumulative exposures over 8 h yield a LEX,8h higher than the mean LAeq; exposures under 8 h yield a lower one. The peak level L_Cpeak (C weighting) is assessed on the worst shift and is not averaged with the peaks of other shifts.

What are the action and limit values?

Art. 189 sets three thresholds: lower action values LEX,8h 80 dB(A) / L_Cpeak 135 dB(C), upper action values 85 / 137, exposure limit value 87 / 140. The overall class is the worse of the LEX,8h and L_Cpeak classes; the limit value is assessed taking into account the attenuation of the hearing PPE worn.

Lower action values    LEX,8h = 80 dB(A)  | LCpeak = 135 dB(C)
Upper action values    LEX,8h = 85 dB(A)  | LCpeak = 137 dB(C)
Exposure limit value   LEX,8h = 87 dB(A)  | LCpeak = 140 dB(C)

The overall class is the worse of the LEX,8h class and the LCpeak class. The exposure limit value (87 dB(A) / 140 dB(C)) is assessed taking into account the attenuation of the hearing PPE worn.

Obligations by band

• Below the lower action values: basic information; no specific obligation.
• Between lower and upper action values: information and training; hearing PPE made available; health surveillance on the worker’s request or if advised by the occupational physician.
• Above the upper action values: hearing PPE mandatory and used; programme of technical and organisational reduction measures; area signage; mandatory periodic health surveillance.
• Beyond the exposure limit value (PPE applied): unacceptable condition; immediate reduction action, investigation of causes, PPE review; suspension of work in serious cases.

Terms

LAeq — A-weighted equivalent continuous level over a measurement interval. For time-varying exposures it is measured by sampling the worker’s activity in representative periods.

PPE applied — the 87 dB(A) limit value is assessed taking into account the effective attenuation of the hearing PPE worn (SNR/HML method or octave bands).

What are the tool’s limitations?

The computation assumes each period’s LAeq is representative of the activity: short or unrepresentative sampling distorts the estimate. It does not consider mechanical vibration or chemical ototoxic agents, handled by other Chapters of D.Lgs 81/08. It computes the nominal LEX,8h, without PPE: device attenuation must be assessed separately.

• The computation assumes each period’s LAeq is genuinely representative of the activity; short or unrepresentative sampling leads to distorted estimates.
• It does not consider exposure to mechanical vibration or to chemical ototoxic agents, handled by other Chapters of D.Lgs 81/08.
• PPE attenuation must be assessed separately; this tool computes the “nominal” LEX,8h, without PPE.

Standards & references

• Italian D.Lgs 9/04/2008 no. 81 — Consolidated Workplace Safety Act, Title VIII Chapter II (protection of workers against noise exposure risks), Art. 187-198.
• ISO 9612:2025 — Acoustics — Determination of occupational noise exposure; supersedes the 2009 edition, withdrawn (measurement methodology).
• Directive 2003/10/EC — minimum safety requirements for workers’ exposure to noise (transposed by D.Lgs 81/08).

Learn more: LEX,8h noise exposure wiki →