A worker is exposed to the following airborne concentrations of ethylbenzene: 8:00 - 10:00 125 ppm 10:15 - 12:15 88 ppm 12:45 - 3:15 112 ppm 3:30 - 5:00 70 ppm What is the 8-hour TWA exposure for the employee (calculate the exposure) ? Does it exceed the OSHA PEL?

Question

Steven

Chemistry

17 June, 13:32

A worker is exposed to the following airborne concentrations of ethylbenzene: 8:00 - 10:00 125 ppm 10:15 - 12:15 88 ppm 12:45 - 3:15 112 ppm 3:30 - 5:00 70 ppm What is the 8-hour TWA exposure for the employee (calculate the exposure) ? Does it exceed the OSHA PEL?

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Mathew Contreras · Answer 1

The 8-hour TWA exposure for the employee is 101 ppm and it exceeds the OSHA PEL of 100 ppm for ethylbenzene.

Explanation:

The TWA for 8 hours is calculated by the sum of airbone concentrations multiplied by the time it has been exposed to that period. The total is divided by 8 which refers to the 8 hours total the employee has been exposed.

TWA = (125x2+88x2+112x2.5+70x1.5) / 8.

The OSHA PEL is a known number for every compound and it can be find in PEL tables. In the case of ethylbenezene, it is 100 ppm.