--- title: "OSHA / NIOSH Noise Limits: TWA / Noise Dose | Aethair" description: "Occupational Noise Exposure (OSHA / NIOSH) limit values for TWA / Noise Dose and Peak Level: every value and averaging period, who the standard applies…" url: https://aethair.io/standards/occupational_noise/ --- Compliance · US OSHA 1910.95 / NIOSH # Occupational Noise Exposure (OSHA / NIOSH) Occupational: hearing conservation Occupational noise standards set how much sound a worker may be exposed to over a shift before hearing protection and a hearing conservation program become mandatory. In the United States two bodies define the framework: the Occupational Safety and Health Administration (OSHA), which sets the enforceable **permissible exposure limit** and the **action level** at which conservation measures begin, and the National Institute for Occupational Safety and Health (NIOSH), which recommends a more protective limit. Exposure is expressed as an 8-hour **time-weighted average (TWA)** in A-weighted decibels, and the limits also cap the **peak** or impulsive sound level. [Schedule a call](https://calendly.com/d/ctdd-mkr-v9v/aethair-demo-website) [Configure OSHA / NIOSH noise Monitoring](https://aethair.io/build/?params=sound_twa,sound_lpeak) At a glance **US OSHA 1910.95 / NIOSH** Occupational: hearing conservation 2 parameters · 4 limit values [TWA / Noise Dose](https://aethair.io/parameters/sound_twa/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) 1 device measures them all - **Thiamis** TSI Noise Monitors [Official text from US OSHA 1910.95 / NIOSH](https://www.osha.gov/noise/standards) The standard ## What Occupational Noise Exposure Limits Are A defining detail is the **exchange rate**: the increase in level that halves the permitted exposure time. OSHA uses a 5 dB exchange rate while NIOSH recommends 3 dB, so the same noise environment can yield different calculated doses depending on which rule applies. The specific levels, action values, and exchange rates are given in the limit table on this page. Limit values ## OSHA / NIOSH noise Limit Values Every value US OSHA 1910.95 and NIOSH publish for the 2 parameters below, with its averaging period, as the standard states it. [**TWA / Noise Dose** Noise](https://aethair.io/parameters/sound_twa/) **90 dBA** *8-hour TWA (OSHA PEL)* 5 dB exchange rate **85 dBA** *8-hour TWA (OSHA action level)* 5 dB exchange rate **85 dBA** *8-hour TWA (NIOSH REL)* 3 dB exchange rate [**Peak Level (Lpeak)** Noise](https://aethair.io/parameters/sound_lpeak/) **140 dBC** *Impulse peak (OSHA ceiling)* Who it applies to ## Who Must Comply Any employer whose workers face sustained loud noise falls under these rules: manufacturing and heavy industry, construction, mining, agriculture, aviation ground operations, entertainment venues, and transport. Where exposures reach the action level, the employer must establish a hearing conservation program: monitoring, audiometric testing, hearing protection, training, and record-keeping. Safety managers and occupational-health teams are responsible for measuring exposures and demonstrating that they stay within the limits, since noise-induced hearing loss is one of the most common and entirely preventable occupational diseases. Monitoring ## How Monitoring Demonstrates Compliance Two complementary measurements establish compliance. **Noise dosimetry** places a small dosimeter on the worker to integrate sound energy across the whole shift, producing the time-weighted average and dose that are compared against the action level and permissible limit. **Area sound-level measurements**, taken with a sound level meter, map noise across a workplace to identify which machines and zones drive exposure and where controls or signage are needed. For defensible results the instrument should meet the relevant [IEC 61672](https://aethair.io/standards/iec_61672/) class and be field-calibrated with an acoustic calibrator before use; peak and impulsive levels are captured alongside the TWA. [Customize this configuration](https://aethair.io/build/?params=sound_twa,sound_lpeak) ### Who measures each parameter | Parameter | Aethair PRO | Aethair IAQ | External | | - | - | - | - | | [TWA / Noise Dose](https://aethair.io/parameters/sound_twa/) | — | — | [1 instrument](https://aethair.io/parameters/sound_twa/) via Thiamis | | [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) | — | — | [2 instruments](https://aethair.io/parameters/sound_lpeak/) via Thiamis | Devices ## Devices That Cover OSHA / NIOSH noise How much of this standard one Aethair monitor covers, followed by the third-party instruments in the sensor catalog that measure its parameters. Each connects to Environet through a Thiamis gateway, which adds whatever the monitor leaves out. Covers both on its own [**TSI SoundPro** Noise Monitors](https://aethair.io/sensors/tsi-noise-monitors/) Covers part of it (combine on one Thiamis) [**Cirrus Research Cirrus** Noise Monitors 1 of 2: Peak Level](https://aethair.io/sensors/cirrus-research-noise-monitors/) Solutions ## Solutions Judged Against OSHA / NIOSH noise ### [Noise Monitoring](https://aethair.io/solutions/noise/) Environmental and occupational sound levels ### [Occupational Safety & Industrial Hygiene](https://aethair.io/solutions/occupational-safety/) Worker exposure, confined space, and heat stress [All solutions](https://aethair.io/solutions/) Article Library ## Articles on OSHA / NIOSH noise ### [How to Choose an Air Quality Monitor: PRO, IAQ, or Thiamis](https://aethair.io/resources/choosing-aethair-monitoring-device/) Compare Aethair PRO, IAQ, and Thiamis to match the right device to your site, from commercial interiors to industrial and fenceline monitoring. [All articles](https://aethair.io/resources/) Questions ## OSHA / NIOSH noise FAQ What is the exchange rate and why does it matter? The exchange rate is the number of decibels by which a sound level must rise to halve the allowable exposure time. OSHA applies a 5 dB exchange rate and NIOSH a 3 dB rate, so a given noise profile can produce a different calculated dose under each. The 3 dB rule, which matches how sound energy actually accumulates, is generally more protective. What is the difference between the action level and the permissible limit? The action level is the exposure at which a hearing conservation program becomes mandatory (monitoring, audiometric testing, and training), while the permissible limit is the maximum exposure allowed before controls or protection must reduce it. Both values appear in the limit table on this page. Do I need a dosimeter or a sound level meter? Both serve different purposes. A dosimeter is worn by the worker to measure personal exposure across a shift for compliance with the TWA limit, whereas a sound level meter measures noise at a point in space to survey the workplace and pinpoint sources. Many assessments use the two together. How do I put together a noise monitoring configuration? Use a personal noise dosimeter for shift-long exposure and a Class 1 or Class 2 sound level meter for area surveys, both field-calibrated. Use the configurator to build a noise assessment configuration and add vibration or dust monitors where the same tasks generate multiple hazards.