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Chapter 4. Division of Industrial Safety Subchapter 7. General Industry Safety Orders Group 15. Occupational Noise and Ergonomics Article 105. Control of Noise Exposure Recordkeeping.
(a) Exposure Measurements.
The employer shall maintain an accurate record of all employee exposure measurements required by Section 5097(b).
(b) Audiometric Tests.
(1) The employer shall retain all employee audiograms obtained pursuant to Section 5097(c) and (d).
(2) This record shall include:
(A) Name and job classification of the employee.
(B) Date of the audiogram.
(C) The examiner's name.
(D) Date of the last acoustic or exhaustive calibration of the audiometer.
(E) Employee's most recent noise exposure assessment.
(c) Audiometric Test Rooms.
The employer shall maintain accurate records of the measurements required by Appendix C, Audiometric Test Rooms, of the background sound pressure levels in audiometric test rooms.
(d) Record Retention. The employer shall retain records required in this section for at least the following periods:
(1) Noise exposure measurement records shall be retained for 2 years.
(2) Audiometric test records shall be retained for the duration of the affected employee's employment.
(e) Access to Records. All records required by this section shall be provided upon request to employees, former employees, representatives designated by the individual employee and any authorized representative of the Chief of the Division. The provisions of Sections 3204(a)-(g) and (h) apply to access to records required by this section.
(f) Transfer of Records. If the employer ceases to do business, the employer shall transfer to the successor employer all records required to be maintained by this section, and the successor employer shall retain them for the remainder of the period prescribed in Section 5100(d).
Authority cited:
Labor Code 142.3
Reference:
Labor Code 142.3
(Amended by Register 83, No. 41.)
Appendix A
Noise Exposure Computation
I. Computation of Employee Noise Exposure
(a) Noise dose is computed using Table A-1 as follows: When the sound level, L, is constant over the entire work shift, the noise dose, D, in percent, is given by: D = 100 C/T where C is the total length of the work day, in hours, and T is the reference duration corresponding to the measured sound level, L, as given in Table A-1 or by the formula shown as a footnote to that table.
(b) When the workshift noise exposure is composed of two or more periods of noise at different levels, the total noise dose over the work day is given by: D = 100 (C1/T1 + C2/T2 +
. . . + Cn/Tn), where Cn indicates the total time of exposure at a specific noise level, and Tn indicates the reference duration for that level as given by Table A-1.
(c) The eight-hour time-weighted average sound level (TWA), in decibels, may be computed from the dose, in percent, by means of the formula: TWA = 16.61 log 10 (D/100) + 90. For an eight-hour workshift with the noise level constant over the entire shift, the TWA is equal to the measured sound level.
(d) A table relating dose and TWA is given in Section II.
Table A-1
A-weighted Reference A-weighted Reference
sound level, Duration sound level, Duration
L (decibel) T (hour) L (decibel) T (hour)
80..................32 106............0.87
81..................27.9 107............0.76
82..................24.3 108............0.66
83..................21.1 109............0.57
84..................18.4 110.............0.5
85..................16 111............0.44
86..................13.9 112............0.38
87..................12.1 113............0.33
88..................10.6 114............0.29
89..................9.2 115............0.25
90..................8 116............0.22
91..................7.0 117............0.19
92..................6.1 118............0.16
93..................5.3 119............0.14
94..................4.6 120............0.125
95..................4 121............0.11
96..................3.5 122............0.095
97..................3.0 123............0.082
98..................2.6 124............0.072
99..................2.3 125............0.063
100..................2 126............0.054
101..................1.7 127............0.047
102..................1.5 128............0.041
103..................1.3 129............0.036
104..................1.1 130............0.031
105..................1
In the above table, the reference duration, T, is computed by
8
T= -----------
2(L-90)/5
where L is the measured A-weighted sound level.
II. Conversion Between "Dose" and "8-Hour Time-Weighted Average" Sound Level.
Noise exposure is usually measured with an audiodosimeter which gives a readout in terms of dose. Dosimeter readings can be converted to an 8-hour time-weighted average sound level (TWA).
In order to convert the reading of a dosimeter into TWA, use Table A-2. This table applies to dosimeters that are set to calculate dose or percent exposure according to the relationships in Table A-1. So, for example, a dose of 91 percent over an eight hour day results in a TWA of 89.3 dB, and a dose of 50 percent corresponds to a TWA of 85 dB.
If the dose as read on the dosimeter is less than or greater than the values found in Table A-2, the TWA may be calculated by using the formula:
TWA = 16.61 log10 (D/100) + 90 where TWA = 8-hour time-weighted average sound level and D = accumulated dose in percent exposure.
Table A-2
Conversion from "Percent Noise Exposure" or "Dose" to "8-Hour Time-Weighted Average Sound Level" (TWA)
Dose or TWA Dose or TWA Dose or TWA
Percent Percent Percent
Noise Noise Noise
Exposure Exposure Exposure
10...... 73.4 116..... 91.1 510..... 101.8
15...... 76.3 117..... 91.1 520..... 101.9
20...... 78.4 118..... 91.2 530..... 102.0
25...... 80.0 119..... 91.3 540..... 102.2
30...... 81.3 120..... 91.3 550..... 102.3
35...... 82.4 125..... 91.6 560..... 102.4
40...... 83.4 130..... 91.9 570..... 102.6
45...... 84.2 135..... 92.2 580..... 102.7
50...... 85.0 140..... 92.4 590..... 102.8
55...... 85.7 145..... 92.7 600..... 102.9
60...... 86.3 150..... 92.9 610..... 103.0
65...... 86.9 155..... 93.2 620..... 103.2
70...... 87.4 160..... 93.4 630..... 103.3
75...... 87.9 165..... 93.6 640..... 103.4
80...... 88.4 170..... 93.8 650..... 103.5
81...... 88.5 175..... 94.0 660..... 103.6
82...... 88.6 180..... 94.2 670..... 103.7
83...... 88.7 185..... 94.4 680..... 103.8
84...... 88.7 190..... 94.6 690..... 103.9
85...... 88.8 195..... 94.8 700..... 104.0
86...... 88.9 200..... 95.0 710..... 104.1
87...... 89.9 210..... 95.4 720..... 104.2
88...... 89.1 220..... 95.7 730..... 104.3
89...... 89.2 230..... 96.0 740..... 104.4
90...... 89.2 240..... 96.3 750..... 104.5
91...... 89.3 250..... 96.6 760..... 104.6
92...... 89.4 260..... 96.9 770..... 104.7
93...... 89.5 270..... 97.2 780..... 104.8
94...... 89.6 280..... 97.4 790..... 104.9
95...... 89.6 290..... 97.7 800..... 105.0
96...... 89.7 300..... 97.9 810..... 105.1
97...... 89.8 310..... 98.2 820..... 105.2
98...... 89.9 320..... 98.4 830..... 105.3
99...... 89.9 330..... 98.6 840..... 105.4
100...... 90.0 340..... 98.8 850..... 105.4
101...... 90.1 350..... 99.0 860..... 105.5
102...... 90.1 360..... 99.2 870..... 105.6
103...... 90.2 370..... 99.4 880..... 105.7
104...... 90.3 380..... 99.6 890..... 105.8
105...... 90.4 390..... 99.8 900..... 105.8
106...... 90.4 400.... 100.0 910..... 105.9
107...... 90.5 410.... 100.2 920..... 106.0
108...... 90.6 420.... 100.4 930..... 106.1
109...... 90.6 430.... 100.5 940..... 106.2
110...... 90.7 440.... 100.7 950..... 106.2
111...... 90.8 450.... 100.8 960..... 106.3
112...... 90.8 460.... 101.0 970..... 106.4
113...... 90.9 470.... 101.2 980..... 106.5
114...... 90.9 480.... 101.3 990..... 106.5
115...... 91.1 490.... 101.5 999..... 106.6
500..... 101.6 500.... 101.6
Authority cited:
Labor Code 142.3
Reference:
Labor Code 142.3
(Amended by Register 84, No. 35.)
Appendix B
Audiometric Measuring Instruments
I. In the event that pulsed-tone audiometers are used, they shall have tone on-time of at least 200 milliseconds.
II. Self-recording audiometers shall comply with the following requirements:
(a) The chart upon which the audiogram is traced shall have lines at positions corresponding to all multiples of 10 dB hearing level within the intensity range spanned by the audiometer. The lines shall be equally spaced and shall be separated by at least 1/4 inch. Additional increments are optional. The audiogram pen tracings shall not exceed 2 dB in width.
(b) It shall be possible to set the stylus manually at the 10-dB increment lines for calibration purposes.
(c) The slewing rate for the audiometer attenuator shall not be more than 6 dB/sec except that an initial slewing rate greater than 6 dB/sec is permitted at the beginning of each new test frequency, but only until the second subject response.
(d) The audiometer shall remain at each required test frequency for 30 seconds (+ 3 seconds). The audiogram shall be clearly marked at each change of frequency and the actual frequency change of the audiometer shall not deviate from the frequency boundaries marked on the audiogram by more than 3 seconds.
(e) It must be possible at each test frequency to place a horizontal line segment parallel to the time axis on the audiogram, such that the audiometric tracing crosses the line segment at least six times at that test frequency. At each test frequency, the threshold shall be the average of the midpoints of the tracing excursions.
Appendix C
Audiometric Test Rooms
Rooms used for audiometric testing shall not have background sound pressure levels exceeding those in Table C-1 when measured by equipment conforming at least to the Type 2 requirements of ANSI S1.4-1971 (R1976), and to the Class II requirements of ANSI S1.11-1971 (R1976).
Table C-1
Maximum Allowable Octave-Band Sound Pressure Levels for Audiometric Test Rooms
Octave-band center
frequency (Hz)............... 500 1000 2000 4000 8000
Sound pressure level (dB)..... 40 40 47 57 62
Authority cited:
Labor Code 142.3
Reference:
Labor Code 142.3
(Amended byRegister 83, No. 41.)
Appendix D
Acoustic Calibration of Audiometers
I. Audiometer calibration shall be checked acoustically, at least annually, according to the procedures described in this Appendix. The equipment necessary to perform these measurements is a sound level meter, octave-band filter set, and a National Bureau of Standards 9A coupler. In making these measurements, the accuracy of the calibrating equipment shall be sufficient to determine that the audiometer is within the tolerances permitted by ANSI S3.6-1969.
(a) Sound Pressure Output Check.
(1) Place the earphone coupler over the microphone of the sound level meter and place the earphone on the coupler.
(2) Set the audiometer's hearing threshold level (HTL) dial to 70 dB.
(3) Measure the sound pressure level of the tones at each test frequency from 500 Hz through 6000 Hz for each earphone.
(4) At each frequency the readout on the sound level meter should correspond to the levels in Table D-1 or Table D-2, as appropriate, for the type of earphone, in the column entitled sound level meter reading.
(b) Linearity Check.
(1) With the earphone in place, set the frequency to 1000 Hz and the HTL dial on the audiometer to 70 dB.
(2) Measure the sound levels in the coupler at each 10dB decrement from 70 dB to 10 dB, noting the sound level meter reading at each setting.
(3) For each 10-dB decrement on the audiometer, the sound level meter should indicate a corresponding 10 dB decrease.
(4) This measurement may be made electrically with a voltmeter connected to the earphone terminals.
(c) Tolerances.
When any of the measured sound levels deviate from the levels in Table D-1 or Table D-2 by 3 dB at any test frequency between 500 and 3000 Hz, 4 dB at 4000 Hz, or 5 dB at 6000 Hz, an exhaustive calibration is advised. An exhaustive calibration is required if the deviations are 15 dB or greater at any test frequency.
Table D-2
Reference Threshold Levels for Telephonics TDH-39 Earphones
Reference Threshold Sound Level
Level for TDH-39 Meter Reading,
Frequency, Hz Earphones, dB dB
500.................... 11.5 81.5
1000.................... 7 77
2000.................... 9 79
3000.................... 10 80
4000................... 9.5 79.5
6000................... 15.5 85.5
Reference Threshold Levels for Telephonics-TDH-49 Earphones
Reference Threshold Sound Level
Level for TDH-49 Meter Reading,
Frequency, Hz Earphones, dB dB
500.................... 13.5 83.5
1000................... 7.5 77.5
2000.................... 11 81.0
3000................... 9.5 79.5
4000................... 10.5 80.5
6000................... 13.5
Authority cited:
Labor Code 142.3
Reference:
Labor Code 142.3
Appendix E
Methods for Estimating the Adequacy of Hearing Protector
Attenuation
I. For employees who have experienced a standard threshold shift, hearing protector attenuation must be sufficient to reduce employee exposure to a TWA of 85 dB. Employers must select one of the following methods by which to estimate the adequacy of hearing protection attenuation.
II. The most convenient method is the Noise Reduction Rating (NRR) developed by the Environmental Protection Agency (EPA). According to EPA regulation, the NRR must be shown on the hearing protector package. The NRR is then related to an individual worker's noise environment in order to assess the adequacy of the attenuation of a given hearing protector. This Appendix describes four methods of using the NRR to determine whether a particular hearing protector provides adequate protection within a given exposure environment. Selection among the four procedures is dependent upon the employer's noise measuring instruments.
III. Instead of using the NRR, employers may evaluate the adequacy of hearing protector attenuation by using one of the three methods developed by the National Institute for Occupational Safety and Health (NIOSH), which are described in the List of Personal Hearing Protectors and Attenuation Data, HEW Publication No. 76-120, 1975, pages 21-37. These methods are known as NIOSH methods #1, #2 and #3. The NRR described below is a simplification of NIOSH method #2. The most complex method is NIOSH method #1, which is probably the most accurate method since it uses the largest amount of spectral information from the individual employee's noise environment. As in the case of the NRR method described below, if one of the NIOSH methods is used, the selected method must be applied to an individual's noise environment to assess the adequacy of the attenuation. Employers should be careful to take a sufficient number of measurements in order to achieve a representative sample for each time segment.
Note: The employer must remember that calculated attenuation values reflect realistic values only to the extent that the protectors are properly fitted and worn.
IV. When using the NRR to assess hearing protector adequacy, one of the following methods must be used:
(a) When using a dosimeter that is capable of C-weighted measurements:
(1) Obtain the employee's C-weighted dose for the entire workshift, and convert to TWA (see Appendix A).
(2) Subtract the NRR from the C-weighted TWA to obtain the estimated A-weighted TWA under the ear protector.
(b) When using a dosimeter that is not capable of C-weighted measurements, the following method may be used:
(1) Convert the A-weighted dose to TWA (see Appendix A).
(2) Subtract 7 dB from the NRR.
(3) Subtract the remainder from the A-weighted TWA to obtain the estimated A-weighted TWA under the ear protector.
(c) When using a sound level meter set to the A-weighting network:
(1) Obtain the employee's A-weighted TWA.
(2) Subtract 7 dB from the NRR, and subtract the remainder from the A-weighted TWA to obtain the estimated A-weighted TWA under the ear protector.
(d) When using a sound level meter set on the C-weighting network:
(1) Obtain a representative sample of the C-weighted sound levels in the employee's environment.
(2) Subtract the NRR from the C-weighted average sound level to obtain the estimated A-weighted TWA under the ear protector.
Authority cited:
Labor Code 142.3
Reference:
Labor Code 142.3
(Amended by Register 83, No. 41.)
Appendix F
Determination and Application of Age Corrections to Audiograms
As permitted by Section 5097(d)(9), increases in an employee's hearing thresholds, as evidenced by an audiogram taken subsequent to a baseline audiogram, may be adjusted (lowered) for presbycusis (hearing loss due to aging). The applicable correction values at various ages and sound frequencies are included in Table F. If the employer chooses to adjust an employee's audiogram pursuant to Section 5097(d)(9), the employer shall follow the procedure described below.
(a) Obtain from Table F the age correction values at each audiometric test frequency of interest (the hearing losses at 2000, 3000, and 4000Hz are relevant to the determination of whether a standard threshold shift, as defined by Section 5097(d)(8), may exist) for the employee by:
(1) Finding the age at which the most recent audiogram was taken and recording the corresponding age correction values; and
(2) Finding the age at which the baseline audiogram was taken and recording the corresponding age correction values.
(b) Subtract the values found in (a)(2) from those found in (a)(1). (The remainders from these subtractions represent the values (in decibels) which may be attributed to aging and are the values by which the most recent audiogram may be adjusted at the respective audiometric test frequencies.)
(c) Subtract the values found in (b) from the hearing threshold values of the most recent audiogram.
When the adjustment of an audiogram for hearing loss due to aging is performed for the purpose of determining whether a standard threshold shift has occurred, the above-described calculations may be restricted to the 2000, 3000, and 4000 Hz frequencies. If the average of the hearing threshold values at 2000, 3000, and 4000 Hz found in step (c), above, is equal to or greater than 10, then the employee has exhibited a standard threshold shift, and the employer must comply with various provisions of Section 5097(d) as well as certain other requirements such as Sections 5098(a)(2)(B)2 and (b)(3).
Table F Age Correction Values in Decibels for Males (M) and Females (F)
Audiometric Test Frequencies (Hz)
Age 1000 2000 3000 4000 6000
M F M F M F M F M F
20 or Younger 5 7 3 4 4 3 5 3 8 6
21........... 5 7 3 4 4 4 5 3 8 6
22........... 5 7 3 4 4 4 5 4 8 6
23........... 5 7 3 5 4 4 6 4 9 7
24........... 5 7 3 5 5 4 6 4 9 7
25........... 5 8 3 5 5 4 7 4 10 7
26........... 5 8 4 5 5 5 7 4 10 8
27........... 5 8 4 5 6 5 7 5 11 8
28........... 6 8 4 5 6 5 8 5 11 8
29........... 6 8 4 5 6 5 8 5 12 9
30........... 6 8 4 6 6 5 9 5 12 9
31........... 6 8 4 6 7 6 9 5 13 9
32........... 6 9 5 6 7 6 10 6 14 10
33........... 6 9 5 6 7 6 10 6 14 10
34........... 6 9 5 6 8 6 11 6 15 10
35........... 7 9 5 6 8 7 11 7 15 11
36........... 7 9 5 7 9 7 12 7 16 11
37........... 7 9 6 7 9 7 12 7 17 12
38........... 7 10 6 7 9 7 13 7 17 12
39........... 7 10 6 7 10 8 14 8 18 12
40........... 7 10 6 7 10 8 14 8 19 13
41........... 7 10 6 8 10 8 14 8 20 13
42........... 8 10 7 8 11 9 16 9 20 13
43........... 8 11 7 8 12 9 16 9 21 14
44........... 8 11 7 8 12 9 17 9 22 14
45........... 8 11 7 8 13 10 18 10 23 15
46........... 8 11 8 9 13 10 19 10 24 15
47........... 8 11 8 9 14 10 19 11 24 16
48........... 9 12 8 9 14 11 20 11 25 16
49........... 9 12 9 9 15 11 21 11 26 16
50........... 9 12 9 10 16 11 22 12 27 17
51........... 9 12 9 10 16 12 23 12 28 17
52........... 9 12 10 10 17 12 24 13 29 18
53........... 9 13 10 10 18 13 25 13 30 18
54........... 10 13 10 11 18 13 26 14 31 19
55........... 10 13 11 11 19 14 27 14 32 19
56........... 10 13 11 11 20 14 28 15 34 20
57........... 10 13 11 11 21 15 29 15 35 20
58........... 10 14 12 12 22 15 31 16 36 21
59........... 11 14 12 12 22 16 32 16 37 21
60 or Older.. 11 14 13 12 23 16 33 17 38 22
Authority cited:
Labor Code 142.3
Reference:
Labor Code 142.3
(Amended by Register 83, No. 41.)