Exposure Assessment and Storage Capacity Calculations questions for the ASP
ASP11 Domain 1: Mathematical Calculations (1.1 Storage capacity; 1.14 Exposure assessments (TWA, mixtures)). 3 free questions below. Every answer quotes and links the formula source it rests on.
Question 1Calculation
Air sampling shows a painter's exposure to acetone during an 8-hour shift was 1 hour at 1127 ppm, 6 hours at 1038 ppm, 1 hour at 134 ppm. Using OSHA's cumulative exposure formula, what is the 8-hour equivalent exposure (E)?
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Answer: D. 936.1 ppm
E = (Ca Ta + Cb Tb + Cc Tc) ÷ 8 = (1127 x 1 + 1038 x 6 + 134 x 1) ÷ 8 = 936.1 ppm. Averaging the three concentrations without weighting by time gives a different, incorrect value.
Answer D rests on
29 CFR 1910.1000(d)(1)(i)(opens ecfr.gov in a new tab)“The cumulative exposure for an 8-hour work shift shall be computed as follows: E = (Ca Ta + Cb Tb + . . .Cn Tn) ÷ 8 Where: E is the equivalent exposure for the working shift. C is the concentration during any period of time T where the concentration remains constant. T is the duration in hours of the exposure at the concentration C.”
Question 2Calculation
Air sampling shows a painter's exposure to acetone during an 8-hour shift was 2 hours at 1421 ppm, 2 hours at 881 ppm, 4 hours at 170 ppm. Using OSHA's cumulative exposure formula, what is the 8-hour equivalent exposure (E)?
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Answer: B. 660.5 ppm
E = (Ca Ta + Cb Tb + Cc Tc) ÷ 8 = (1421 x 2 + 881 x 2 + 170 x 4) ÷ 8 = 660.5 ppm. Averaging the three concentrations without weighting by time gives a different, incorrect value.
Answer B rests on
29 CFR 1910.1000(d)(1)(i)(opens ecfr.gov in a new tab)“The cumulative exposure for an 8-hour work shift shall be computed as follows: E = (Ca Ta + Cb Tb + . . .Cn Tn) ÷ 8 Where: E is the equivalent exposure for the working shift. C is the concentration during any period of time T where the concentration remains constant. T is the duration in hours of the exposure at the concentration C.”
Question 3Calculation
Air sampling shows a painter's exposure to n-butyl acetate during an 8-hour shift was 4 hours at 113 ppm, 3 hours at 110 ppm, 1 hour at 66 ppm. Using OSHA's cumulative exposure formula, what is the 8-hour equivalent exposure (E)?
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Answer: A. 106.0 ppm
E = (Ca Ta + Cb Tb + Cc Tc) ÷ 8 = (113 x 4 + 110 x 3 + 66 x 1) ÷ 8 = 106.0 ppm. Averaging the three concentrations without weighting by time gives a different, incorrect value.
Answer A rests on
29 CFR 1910.1000(d)(1)(i)(opens ecfr.gov in a new tab)“The cumulative exposure for an 8-hour work shift shall be computed as follows: E = (Ca Ta + Cb Tb + . . .Cn Tn) ÷ 8 Where: E is the equivalent exposure for the working shift. C is the concentration during any period of time T where the concentration remains constant. T is the duration in hours of the exposure at the concentration C.”
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