Cal. Code Regs. tit. 8, § 5096 – Exposure Limits for Noise.

(a) Protection against the effects of noise exposure shall be provided when the sound levels exceed those shown in Table N-1 of this section when measured on the A-scale of a standard sound level meter at slow response.
(b) When employees are subjected to sound levels exceeding those listed in Table N-1 of this section, feasible administrative or engineering controls shall be utilized. If such controls fail to reduce sound levels within the levels of the table, personal protective equipment shall be provided and used to reduce sound levels within the levels of the table.
Table N-1 Permissible Noise Exposure¹
Permitted Duration
Permitted Duration
Sound Level
Per Workday (hours-
per Workday Sound Level
(hours-
(dBA)
minutes)
hours
(dBA)
minutes)
hours
90
8-0
8.00
103
1-19
1.32
91
6-58
6.96
104
1-9
1.15
92
6-4
6.06
105
1-0
1.00
93
5-17
5.28
106
0-52
0.86
94
4-36
4.60
107
0-46
0.76
95
4-0
4.00
108
0-40
0.66
96
3-29
3.48
109
0-34
0.56
97
3-2
3.03
110
0-30
0.50
98
2-38
2.63
111
0-26
0.43
99
2-18
2.30
112
0-23
0.38
100
2-0
2.00
113
0-20
0.33
101
1-44
1.73
114
0-17
0.28
102
1-31
1.52
115
0-15
0.25
1 When the daily noise exposure is composed of two or more periods of noise exposure of different levels, their combined effect should be considered, rather than the individual effect of each. If the sum of the following fractions: C₁/T₁ + C₂/T₂ ... C_n/T_n exceeds unity, then, the mixed exposure should be considered to exceed the limit value. C_n indicates the total time of exposure at a specified noise level, and T_n indicates the total time of exposure permitted at that level.
(c) If the variations in noise level involve maxima at intervals of 1 second or less, the noise is to be considered continuous.
(d) Exposure to impulsive or impact noise should not exceed 140 dB peak sound pressure level.

Note: Authority cited and Reference: Section 142.3, Labor Code.