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Facts About Noise #2

Permissible Noise Exposure

The legally permissible noise exposure varies from country to country. U.S. law currently allows exposure to 90 dB for eight hours. Most countries allow only 85 dB for an eight hour work day.

Scientifically noise doubles with every increase of three dB, but U.S. legislation has defined a five dB doubling for legal purposes. This definition allows more noise exposure and consequently require less efforts form corporations in regards to noise abatement and hearing conservation efforts.

Discussions and proposals are now ongoing in the U.S. to lower the maximum noise level to 85 dB and also to accept the three dB doubling factor. The two charts below show the differences in legal noise exposure for the four possible scenarios.

Example: 90 dB and 85 dB for 8 hours, with 5 dB doubling factor

Noise Level	Maximum Legal Exposure	Noise Level	Maximum Legal Exposure
90 dB	8 hours	85 dB	8 hours
95 dB	4 hours	90 dB	4 hours
100 dB	2 hours	95 dB	2 hours
105 dB	1 hour	100 dB	1 hour
110 dB	30 minutes	105 dB	30 minutes
115 dB	15 minutes	110 dB	15 minutes
120 dB	7.5 minutes	115 dB	7,5 minutes

Example: 90 dB and 85 dB for 8 hours, with 3 dB doubling factor

Noise Level	Maximum Legal Exposure	Noise Level	Maximum Legal Exposure
90 dB	8 hours	85 dB	8 hours
93 dB	4 hours	88 dB	4 hours
96 dB	2 hours	91 dB	2 hours
99 dB	1 hour	94 dB	1 hour
102 dB	30 minutes	97 dB	30 minutes
105 dB	15 minutes	100 dB	15 minutes
108 dB	7.5 minutes	103 dB	7.5 minutes
111 dB	3.75 minutes	106 dB	3.75 minutes
114 dB	1.87 minutes	109 dB	1.87 minutes

Facts About Noise #2

Permissible Noise Exposure

Example: 90 dB and 85 dB for 8 hours, with 5 dB doubling factor

Example: 90 dB and 85 dB for 8 hours, with 3 dB doubling factor

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