EN 352: Hearing protection - General requirements

EN 352 The European Standard for protection against noise is made in several parts for the safety and testing on different types of individual noise protectors.
The different types can be identified using the extension following EN 352, for example: EN 352-1.

● EN 352-1 for Ear Muffs
● EN 352-2 for Ear Plugs and Ear Moulds
● EN 352-3 for Helmet Mounted Ear Muffs
● EN 352-4 for Level Dependent Ear Muffs
● EN 352-5 for Active Noise Reduction Ear Muffs
● EN 352-6 for Ear Muffs with Electrical Audio Inputs
● EN352-7 for Level Dependent Ear Plugs

Definitions:
Ear defenders or ear muffs: PPE designed to protect the wearer from extreme noise. The head-band and outer covering is usually made from hard thermoplastic or metal, and the protection is from acoustic foam which absorbs sound waves by increasing air resistance, thus reducing the amplitude of the waves.
dB (A): Decibels. Main unit used for the power level or intensity level of the sound. The daily exposure of a worker to the noise, daily level of equivalence, is expressed in dB (A), calculated and referred to 8 hours a day. Because the human ear can register sounds across an extensive range of intensity, a linear scale is not suitable for measurement. The dB scale is therefore a log scale in which the sound intensity roughly doubles for every 3 dB increase. An increase of 20 dB would increase the sound intensity 100 times, (i.e., 60 dB is 100 times louder than 40 dB).
Peak acoustic pressure: A measure of the maximum instantaneous sound pressure at a specified location. Exposure to high peak sound levels can be associated with immediate damage to hearing.
Daily exposure level to the noise (LEX, 8h) (dB (A), ref 20 μPa): is the sound exposure averaged over 8 hours. •the levels of exposure to noise of employees averaged over a working day or week; and
•the maximum noise (peak sound pressure) to which employees are exposed in a working day.
SNR “Simplified Noise level Reduction” or “Single Number Rating”: Is an ear defender average sound noise reduction. It is generally used to compare different types of hearing protectors. The higher the SNR, the higher the level of noise attenuation provided by the hearing protection.
HML is “High, Medium and Low” and defines the protection at high, medium and low frequencies.

Important limits within the law:
• Noise 80 dB(A) – Noise level preferably lie between 70 -80 dB.
• Noise 85 dB(A) - Hearing protection is required.
• Noise 87 dB(A) - This limit may not be exceeded.

Actions to be taken per limit:
Sound level 80 dB(A)
• Determine the degree of risk of exposure to the sound
• Take measures to reduce exposure
• Inform staff about the risks
• Ensure that proper training and information is provided about the risks and measures
• Audiometric testing is required if the risks may endanger health

Sound level 85 dB(A)
• Determine the degree of risk of exposure to the sound
• Take measures to reduce exposure
• Inform staff about the risks
• Ensure that proper training and information is provided about the risks and measures
• Hearing protection is required
• Audiometric testing is a requirement

Sound level 87 dB(A)
• This threshold value must not be exceeded under any conditions
• All sound measurements are carried out inside the ear; in other words, the level of 87 dB(A) must not be exceeded if hearing protection is already being worn

How long can you be exposed to a specified level of sound?

Sound Pressure in dB(A) Safe length of exposure
80dB(A) 8 hours
83dB(A) 4 hours
86dB(A) 2 hours
89dB(A) 1 hours
92dB(A) 30 minutes
95dB(A) 15 minutes
98dB(A) 7 minutes and 30 seconds
101dB(A) 3 minutes and 45 seconds
104dB(A) 2 minutes
107dB(A) 1 minute