Noise exposure limits and controls

Protection is required whenever measured sound levels exceed the values in Table D-2. The regulation at 1926.52(a) requires protection when sound levels, measured on the A‑scale of a standard sound level meter at slow response, exceed the table values.

• Measure using an A‑weighted sound level meter on slow response per 1926.52(a).
• If the measured level is higher than the table value for the employee’s daily exposure time, the employer must take action under 1926.52(b).

The permissible noise exposures are the levels in Table D-2; an 8‑hour exposure limit is 90 dBA and shorter durations allow higher dBA. 1926.52(d) and Table D‑2 list these limits.

• 8 hours — 90 dBA
• 6 hours — 92 dBA
• 4 hours — 95 dBA
• 3 hours — 97 dBA
• 2 hours — 100 dBA
• 1½ hours — 102 dBA
• 1 hour — 105 dBA
• ½ hour — 110 dBA
• ¼ hour or less — 115 dBA

Use these values when planning controls and PPE to keep workers at or below the permissible exposure for their daily duration as required by 1926.52(d).

You combine exposures using the equivalent noise exposure factor (Fe) formula; if Fe exceeds 1, the exposure exceeds the permissible limit. The formula in 1926.52(d)(2)(ii) is Fe = (T1/L1) + (T2/L2) + … + (Tn/Ln), where T is the time at a constant level and L is the allowable duration for that level from Table D‑2.

• If Fe > 1 → exposure exceeds permissible levels.
• If Fe ≤ 1 → exposure is within permissible limits.

Yes — using the sample in the standard, the combined exposure can be computed and compared to unity. 1926.52(d)(2)(iii) provides an example:

• 110 dBA for 1/4 hour (Table D‑2 allows 1/2 hour at 110 dBA): 0.25 / 0.5 = 0.5
• 100 dBA for 1/2 hour (Table D‑2 allows 2 hours at 100 dBA): 0.5 / 2 = 0.25
• 90 dBA for 1½ hours (Table D‑2 allows 8 hours at 90 dBA): 1.5 / 8 = 0.188
• Fe = 0.500 + 0.25 + 0.188 = 0.938 → Fe ≤ 1, so the exposure is within permissible limits per 1926.52(d)(2)(iii).

Treat noise with maxima at intervals of 1 second or less as continuous. 1926.52(c) states that variations with peaks occurring at intervals of 1 second or less are considered continuous for compliance and measurement purposes.

• This affects measurement (use slow response A‑scale) and how you apply durations from Table D‑2.

Impulsive or impact noise must not exceed 140 dB peak sound pressure level. 1926.52(e) sets a 140 dB peak limit for impulsive/impact noise; exposures above that peak require controls to reduce the peak level.

Employers must use feasible administrative or engineering controls when noise exceeds Table D‑2 levels, and provide hearing protectors only if those controls fail to reduce noise to within the table. 1926.52(b) requires feasible engineering or administrative controls first; if those controls do not bring exposures within Table D‑2 values, the employer must provide personal protective equipment under Subpart E (see 1926.52(b)).

• The practical approach is: attempt engineering controls (isolation, enclosure, quieter tools), then administrative (job rotation, shorter shifts), and provide PPE if exposures still exceed the table limits.

A continuing, effective hearing conservation program is required whenever the sound levels exceed the values in Table D‑2. 1926.52(d)(1) directs employers to administer a continuing, effective hearing conservation program in all cases where sound levels exceed the table values.

• Note: For general industry, OSHA’s hearing conservation amendment uses an 85 dBA action level (see the discussion in OSHA’s letter on noise and hearing conservation at https://www.osha.gov/laws-regs/standardinterpretations/2023-03-06). Construction employers should follow 1926.52(d)(1) for the construction-specific requirement.

Use a standard sound level meter on the A‑scale at slow response. 1926.52(a) requires measurement on the A‑scale of a standard sound level meter at slow response to determine if levels exceed the Table D‑2 values.

• Do not rely on peak C‑ or Z‑weighted quick measurements for the Table D‑2 comparison; use A‑scale slow response as specified.

Treat the combined effect of the different exposure periods rather than each one separately and compute Fe. 1926.52(d)(2)(i) requires employers to consider the combined effect of multiple exposure periods and to compute exposure using the formula in 1926.52(d)(2)(ii).

• For planning, list each task level and duration, find the allowable duration for that dBA in Table D‑2, compute T/L for each, and sum them to get Fe.

An Fe value equal to 1 is within permissible limits; only values that exceed unity exceed the permissible exposure. 1926.52(d)(2)(ii) states that if Fe exceeds unity (1), the exposure exceeds permissible levels — so Fe = 1 is acceptable.

• Use Fe > 1 as the threshold requiring additional controls or PPE.

The employer must prevent impulsive or impact noise from exceeding 140 dB peak by using controls or, if necessary, PPE. 1926.52(e) states the 140 dB peak limit; exposures above that level require measures (engineering, administrative, or appropriate PPE) to reduce the peak so it does not exceed 140 dB.

• Consider engineering fixes (barriers, maintenance), administrative adjustments (distance, timing), and compliant hearing protection if controls cannot eliminate the peak.

If engineering or administrative controls cannot reduce noise to Table D‑2 levels, the employer must provide and require the use of personal protective equipment under Subpart E. 1926.52(b) requires feasible engineering or administrative controls first; if those fail, the employer must provide PPE (per Subpart E) to reduce exposures to within the table levels.

• Employers should also follow applicable PPE selection and hazard assessment practices; see OSHA’s PPE hazard assessment guidance at https://www.osha.gov/laws-regs/standardinterpretations/2024-03-28 for how to document hazard assessments and select PPE.

Noise‑canceling headphones are not automatically approved; the employer must ensure any hearing protector reduces exposure to or below the permissible level for the worker’s exposure. OSHA’s policy allows reliance on hearing protection devices when they effectively attenuate noise, but the device must achieve the necessary attenuation to reduce exposure to the applicable limit (see OSHA’s discussion on noise and hearing protection at https://www.osha.gov/laws-regs/standardinterpretations/2023-03-06 and the construction requirements in 1926.52).

• Verify attenuation: choose a device with sufficient Noise Reduction Rating (NRR) or validated attenuation, ensure correct fit and worker acceptance, and include it in a hearing program required by 1926.52(d)(1).

If maxima occur at 1 second intervals or less, treat the noise as continuous and measure with an A‑scale slow response meter as required in 1926.52(a) and per 1926.52(c).

• Use the continuous-exposure approach and apply Table D‑2 durations and the Fe formula in 1926.52(d)(2)(ii) to determine compliance.

Select the table value that corresponds to the nearest listed sound level or use professional measurement practice to interpolate; the regulation requires using Table D‑2 durations for the constant levels in the Fe formula (1926.52(d)(2)(ii)).

• If measurement yields a level not exactly matching a Table D‑2 row, use the closest appropriate table duration or consult an industrial hygienist to determine the correct L value for computing Fe.

Not initially; employers must try feasible engineering or administrative controls first and may rely on hearing protectors only if those controls fail to bring levels within Table D‑2. 1926.52(b) requires using feasible engineering or administrative controls, and if those do not reduce noise to the table values, the employer must provide PPE (Subpart E). OSHA guidance also notes employers may rely on hearing protection devices when they effectively attenuate noise (see https://www.osha.gov/laws-regs/standardinterpretations/2023-03-06), but that reliance comes after attempting controls.

Calculate the worker’s Fe using each exposure period and the Table D‑2 allowable durations; if Fe > 1, reduce exposures through controls or PPE. For example: 95 dBA for 4 hours and 90 dBA for 2 hours → Fe = (4/4) + (2/8) = 1 + 0.25 = 1.25, which exceeds unity, so exposures are not permissible under 1926.52(d)(2)(ii).

• If Fe > 1, implement engineering/administrative controls per 1926.52(b) or provide properly chosen and fit hearing protectors as required.

The employer is responsible for assessing noise hazards and selecting PPE based on that assessment; qualified personnel or industrial hygienists should perform sound measurements and hazard assessments. 1926.52(a) sets the measurement method, and OSHA guidance on PPE hazard assessment (see https://www.osha.gov/laws-regs/standardinterpretations/2024-03-28) explains the employer must assess hazards and provide written certification when PPE will be required.

• Document the noise survey, the durations used for Fe calculations, and the rationale for the selected hearing protection.