This is precisely the case if the 3 dBA exchange rate is used. It follows, then, that the allowable time should be halved for every 3 dBA increase in sound level. They argue that it is logical that if the sound level is doubled, then the allowable exposure time should be cut in half. Most experts recognize the 3 dB rule as more logical. With the 5 dBA exchange rate, it is one hour. For example, the maximum permitted duration for a 100 dBA noise exposure in the 3 dBA exchange rate is 15 minutes. The 3 dBA exchange rate is more stringent. There are two types of exchange rates currently in use: 3 dBA exchange rate or the "3 dB rule," and 5 dBA exchange rate or the "5 dB rule." These two exchange rates, with criterion levels of 85 dBA and 90 dBA, give two different sets of exposure guidelines, as Table 1A and 1B show. The allowed maximum exposure time is calculated by using an exchange rate, also called a "dose-trading relation" or "trading ratio." The exchange rate is the amount by which the permitted sound level may increase if the exposure time is halved. This criterion level is 85 dBA in most jurisdictions, but it is 87 dBA for organizations that follow the Canadian federal noise regulations.Īs the sound level increases above the criterion level, Lc, the allowed exposure time must be decreased. The criterion level, often abbreviated as Lc, is the steady noise level permitted for a full eight-hour work shift. Noise Exposure Limits when Criterion Level = 90 dBA Noise Exposure Limits when Criterion Level = 85 dBA The OELs depend on two key factors that are used to prepare exposure-duration tables: the criterion level and the exchange rate. They are often displayed in exposure-duration tables like Table 1A and Table 1B. Occupational exposure limits (OELs) for noise are typically given as the maximum duration of exposure permitted for various noise levels. What are the occupational exposure limits for workplace noise? Back to top You are here: Noise - Occupational Exposure Limits in Canada
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