2. (25%) One group of workers in a factory are exposed to a noise level of 110 dB(A) for 8 hours. In the adjoining work area, their colleagues are exposed to 70 dB(A) for 8 hours. Management proposes introducing job rotation (everyone Works for 4 hours in the noisy area and 4 hours in the quieter area) to bring the 8-hour exposure down to 90 dB(A), on average, for everyone.
a. (10%) Will management’s proposal work? If not, show what the new noise dose will be.
b. (15%) You recommended that workers in the noisy area should wear ear muffs which will reduce the noise by 30 dB(A), but workers feel uncomfortable with the ear muffs and take them off for one hour during 8hr shift while they are working. Would you go alone with your proposal or make a new proposal? Why? Please justify your answer.
(You may use the following formulas and table as appropriate)
D = 100 (C(1)/T(1) + C(2)/T(2) + … + C(n)/T(n))
TWA = 16.61 log(10) (D/100) + 90
TABLE G-16A Reference
A-weighted sound level, ———Duration T (hour)
80……………………………………………………………………… 32
85……………………………………………………………………… 16
90……………………………………………………………………….. 8
95………………………………………………………………………. 4
100……………………………………………………………………. 2
105……………………………………………………………………… 1
110……………………………………………………………………….. 0.5
115………………………………………………………………………. 0.25
116……………………………………………………………………… 0.22
117……………………………………………………………………….. 0.19
120… …………………………………………………………………..0.125
125…………………………………………………………………………. 0.063
127……… …………………………………………………………………..0.047
130……………………………………………………………………………… 0.031
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