Noise daily personal exposure

The first action level is a daily personal noise exposure of 85 dB, expressed as 85dB(A). 

In general the noise level in the community or inside a factory will vary with time. The equivalent noise level is defined as the notional steady noise level which, over a given period of time, would deliver the same amount of sound energy as the fluctuating level. Thus to maintain the Leg when SPL is doubled, exposure time must be halved (Table 20.2). The equivalent noise level concept forms the basis of the exposure criteria used in the Noise at Work Regulations 1989 which calls it daily personal noise exposure (Lep,ci). Where the fluctuation is not well defined the calculations can be done electronically using a dosimeter or statistical analyser. Transient noises also require statistical analysis and those measurements often required are ... 

For variable noise exposure, however, the daily personal noise exposure (LRpd) must be calculated. 

A spreadsheet was developed to collect data from the field. To estimate the daily personal noise exposure defined in accordance with the gathered information, a characterization of the productive process regarding the distribution of the different work stations/task, was made. For that purpose, an interval time of exposure was assigned. 

LEP,d measures a worker s daily personal exposure to noise, expressed in dB(A). LEP,w is the measure of the worker s weekly average of the daily personal noise exposure, again expressed in dB(A). 

First action level - daily personal noise exposure (LEP,d) of 85dB(A)... 

Another important noise measurement is the daily personal exposure level of the worker, l-EP,d> which is measured over an 8-hour working day. Hence, if a person was exposed to 87dB(A) over 4 hours, this would equate to a Lep.ci of 84dB(A) since a reduction of 3 dB(A) represents one half of the noise dose. 

If the daily noise exposure exceeds the lower action level, then a noise assessment should be carried out and recorded by a competent person. There is a very simple test which can be done in any workplace to determine the need for an assessment. 

In Brazil, the NR-15 is the standard that defines maximum exposure levels without the need for the use of Personal Protective Equipment (PPE) or Collective Protective Equipment (CPE) and it states that a continuous noise of 85 dB is the maximum tolerated for an exposition for 8 hours of a daily work journey. Above these values, the exposure time should be reduced, or control measures must be adopted, because thus it begins to present risks to workers (Lombardi et al. 2011). 

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