Aworker 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?

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.