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Noise Exposure - Permissible Level and Duration

Noise exposure should be controlled so that exposure is less than the combination of exposure level and duration

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

The maximum time of exposure can be calculated as:

t = 28,800 / 2(L - 85)/3         (1)

where

t = maximum exposure duration (seconds)

L = exposure level (dBA)

3 = exchange rate (dB)

85 = Recommended Exposure Limit - REL

maximum human noise exposure time diagram

Combinations of noise exposure levels and maximum duration time are expressed in the table below:

Exposure Level
(dBA)		 Duration Time - t - (s)
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

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