For Kim Woods Only

Industrial Hygiene: Week VIII Assessment

1. You are an industrial hygienist conducting personal sampling on a worker who is overseeing a

production process involving use of acetone (Note: The Occupational Safety and Health

Administration has established a Permissible Exposure Limit of 1000 parts per million (ppm) of

acetone). You are able to measure the following exposures:

700 ppm for 3 hours

1300 ppm for 2 hours

900 ppm for 3 hours

What is the calculated TWA? What would you tell plant management in terms of exposure to

acetone and compliance with the PEL?

2. Please solve the following problem, indicating your response on a Word document.

Using the following formula, solve the problem below, and show your work.

TWA = CaTa + CbTb + ... + CnTn

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Note: All concentrations are in parts contaminant per million parts of air or milligrams of contaminant per

cubic meter of air.

Air Sampling Problem: You are an industrial hygienist that is conducting personal sampling on a worker

who is overseeing a production process involving use of toluene (Note: The Occupational Safety and

Health Administration has established a Permissible Exposure Limit of 200 parts per million (ppm)). You

are able to measure the following exposures:

500 ppm for 1 hour

100 ppm for 4 hours

225 ppm for 3 hours

What is the calculated TWA? What would you tell plant management in terms of exposure to toluene and

compliance with the PEL?

TWA = Time-Weighted Average

Ca = Concentration of contaminant during the sampling period "a"

Ta = Time of sampling period "a"

Cb = Concentration of contaminant during the sampling period "b"

Tb = Time of sampling period "b"

Cn = Concentration of contaminant during the sampling period "n", where "n" is the last of a series

of contaminants

Tn = Time of sampling period "n"