Noise Exposure - NIOSH Permissible Levels and Duration

Exposure to noise should be controlled so that it is less than a maximum combination of exposure level and duration.

According the National Institute for Occupational Safety - NIOSH - the exposure to noise should be controlled so that the exposure is less than a max combination of exposure level - L - and duration - t.

The maximum time of exposure at a noise level can be calculated as:

t = 480 / 2^{(L - 85)/3} (1)

where

t = maximum exposure duration (minutes)

L = noise exposure level (dB(A))

3 = exchange rate (dB)

Maximum human noise exposure - time diagram

Download and print Noise Level - Maximum Exposure Time Chart

Example - Maximum Exposure Time to Noise

The maximum time a person can be exposed for a noise level 100 dB can be calculated as

t = 480 / 2^{((100 dB) - 85)/3}

= 15 minutes

Maximum Noise Exposure Time Calculator

L - noise exposure level (dB(A))

Combinations of noise exposure levels and maximum duration time:

Maximum Duration Time vs. Noise Level and Exposure Time
Noise Exposure Level (dB_A)	Duration Time
Noise Exposure Level (dB_A)	Hours	Minutes	Seconds
80	25	24
81	20	10
82	16
83	12	42
84	10	5
85	8
86	6	21
87	5	2
88	4
89	3	10
90	2	31
91	2
92	1	35
93	1	16
94	1
95		47	37
96		37	48
97		30
98		23	49
99		18	59
100		15
101		11	54
102		9	27
103		7	30
104		5	57
105		4	43
106		3	45
107		2	59
108		2	22
109		1	53
110		1	29
111		1	11
112			56
113			45
114			35
115			28
116			22
117			18
118			14
119			11
120			9
121			7
122			6
123			4
124			3
125			3
126			2
127			1
128			1
129			1
130			1
-140			< 1

Daily Noise Dose Level - Daily noise dose when exposed in periods with different noise levels