Answer

Industrial Hygiene Questions

TWA Calculation for the Workers

Worker 1:

The dose is calculated by the formula below:

Dose = 100 x (C1/T1 + C2/T2 + C3/T3 + … + Cn/Tn)

Appendix A of Table G16-A outlines that:

80.5 dBA is equivalent to 81 or 27.9

81.0 dBA is equivalent to 81 or 27.9

82.0 dBA is equivalent to 82 or 24.3

95.0 dBA is equivalent to 95 or 4

Therefore;

Dose = 100 x (3/27.9 + 2/27.9 + 2/24.3 + 1/4) = 51.1516%

The formula for calculating TWA is 16.61 log(10)(D/100) + 90

Therefore, for Worker 1, TWA = 16.61 log(10)(51.1516/100) + 90 = 85.16415 = 85.1

Worker 1 TWA= 85.1 Dba

Worker 2:

The dose is calculated by the formula below:

Dose = 100 x (C1/T1 + C2/T2 + C3/T3 + … + Cn/Tn)

Appendix A of Table G16-A outlines that:

98.5 dBA is equivalent to 99 which is equal to 2.3

86.5 dBA is equivalent to 87 which is equal to 12.1

84.5 dBA is equivalent to 85 which is equal to 16

83.5 dBA is equivalent to 84 which is equal to 18.4

Therefore;

Dose = 100 x (3/2.3 + 2/12.1 + 2/16 + 1/18.4) = 164.89849%

Worker 2’s TWA= 16.61 log(10)(164.89849/100) + 90 = 93.60797 = 93.6 dBA

Worker 3:

Appendix A of Table G16-A outlines that:

92.5 dBA is equivalent to 93 which is equal to 5.3

85.0 dBA is equivalent to 85 which is equal to 16

83.5 dBA is equivalent to 84 which is equal to 18.4

80.0 dBA is equivalent to 80 which is equal to 32

Therefore;

Dose = 100 x (3/5.3 + 2/16 + 2/18.4 + 1/32) = 83.09834%

Worker 3’s TWA= 16.61 log(10)(83.09834/100) + 90 = 88.66443 = 88.6 dBA

OSHA’s Permissible Limit

            Worker 2’s exposure exceeds the set permissible limit by OSHA which is estimated at 90 dBA for an 8-hour period (Occupational Safety and Health Administration (OSHA), n.d). Worker 2’s TWA is 93.6 dBA. Therefore, the company should consider a hearing conservation program in the case of this worker to avoid potential damages. Hearing aids can be used to reduce sound levels and potential damage.

Factors Influencing the Accuracy of Noise Measurements

            Temperature and background noise are some of the common factors which can influence the accuracy of noise measurement. Moreover, proximity to the noise source can also affect the derived figures. Therefore, the measuring equipment should always be calibrated prior and after the noise readings are taken. Also, the measuring equipment should be available at a shoulder level and within a distance of 2-feet from the person being monitored to prevent interferences from background noise (Canadian Centre for Occupational Health (CCOH), 2018).