Noise is a common problem in workplaces around the world. But nobody should be at risk of injury at work. That is why there are official limits in place to regulate workplace noise. Here is a brief introduction to the types and levels of noise subject to regulation.
Different countries make different interpretations of the risks of occupational noise-induced hearing disorder. Below are a few examples of countries and their national regulation* of the 8-hour average exposure and the upper limit for peak sound pressure level. Consult your local legislation for noise levels in your country.
Although noise limits vary from country to country, there is a generally accepted standard of a time-weighted average (TWA) of 85 dB (A). TWA is a method of calculating workers’ daily exposure to noise as the average over an 8-hour work day, or a 40-hour work week.
A-weighting, written dB (A), accounts for the loudness as perceived by the human ear, as the ear is less sensitive to low frequencies. A-weighting mimics how humans perceive noise below 100 decibels. When measuring noise with a sound level meter, frequencies between 500 and 10 000 Hz are measured, filtering the lower frequencies which are not usually heard by the human ear.
The longer the exposure time, the greater the risk of harm. If a worker is exposed to noise below the 85 dB (A) limit for 8 hours, there should be no negative impact on hearing, although caution is called for due to individual differences. At noise levels above the 85 dB (A) limit, the exposure time must be reduced to protect the worker's hearing.
In addition to time-weighted average, many countries have implemented an exposure limit value for peak sound pressure (see table above). This refers to a noise level that no worker should be exposed at any given time, and is therefore not weighted by time. According to EU’s Directive 2003/10/ECs, employers must ensure that no employee is exposed to a peak sound pressure higher than 137 dB (A) at any time of the workday.
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* National and international regulations may change over time. Please consult your local regulation for the latest update.Source: Sound levels and their relevance, Occupational Safety and Health (IOSH)
https://iosh.com/health-and-safety-professionals/improve-your-knowledge/occupational-health-toolkit/noise/sound-levels-and-their-relevance/
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