How to Evaluate Noise Exposure
The first step toward solving any noise problem is to define it. To understand what requirements must be implemented according to OSHA’s noise standard, it is necessary to determine exposure levels. The following sections provide information about evaluating noise exposure levels:
- Walk-around Survey
- Work-shift Sampling
- Instruments Used to Conduct a Noise Survey
Walk Around Survey
A walk-around survey should be performed to screen for noise exposures and to determine if additional monitoring is necessary. When screening for noise exposures, sound level meter measurements and estimates of the duration of exposure are sufficient. The resulting spot readings can be used to determine the need for a more thorough evaluation.
If the results of the walk-around survey indicate time-weighted average (TWA) exposures of 80 dBA or more, then additional noise monitoring should be performed.
When the results of the walk-around survey indicate that the noise levels may exceed those outlined in OSHA’s noise standard, additional monitoring is necessary. Establish a sampling protocol for your workplace. A general protocol is provided as an example below.
- Inform the employee being monitored that the dosimeter (noise sampling equipment) should not interfere with his/her normal duties, and emphasize that the employee should continue to work as usual.
- Explain the purpose of the dosimeter to each employee being sampled and emphasize that the dosimeter is not a speech recording device.
- Instruct the employee being sampled not to remove the dosimeter unless absolutely necessary and not to cover the microphone with a coat or outer garment or move it from its installed position. Inform the employee when and where the dosimeter will be removed.
- Check the dosimeter periodically to ensure the microphone is properly oriented.
- Obtain and note sound level meter readings during different phases of work the employee performs during the shift.
- Record the information required on the OSHA-92 Noise Survey Report.
Personal and Area Monitoring
Personal monitoring: A sound level meter can also be positioned within the immediate vicinity of the exposed worker to obtain an individual exposure estimate.
Area monitoring: This method can be used to estimate noise exposure when the noise levels are relatively constant and employees are not mobile. In workplaces where employees move about in different areas or where the noise intensity tends to fluctuate over time, noise exposure is generally more accurately estimated by the personal monitoring approach.