1. A worker has been improperly storing 150 mL bottles of ethyl acetate in the basement of an industrial facility. The room is approximately 10 ft. x 10 ft. x 10 ft. and has no ventilation when the doors are closed (assume no leaks). One night 1 bottle is knocked off of the shelf and breaks.
a. Calculate the concentration using the room dimensions and density of nhexane. Assume all the n-hexane has vaporized.
b. Is this concentration above the TLV? Assume that cleaning up the broken bottles will take approximately 30 minutes. Select gloves and a respirator for this clean-up process. For respirator selection, unless absolutely necessary, avoid positive pressure respirators. Select a respirator that has the highest APF with the lowest cost.
c. Based on the respirator you selected calculate the MUC. Is this value protective enough?
d. Based on the concentration in the room how long can the worker wear the respirator without the risk of chemical breakthrough? Is this enough time to clean up the room?
e. What is the permeation rate of the gloves you selected? Is this less than the time it will take to clean up the spill? If not recommend a change out schedule.
2) In Washington State, gasoline powered forklifts are being used to move apples into a cold storage warehouse. The dimensions of the warehouse are 100 ft. x 55 ft. x 10 ft. (15 pts.) a. How does OSHA recommend sampling for CO? Principles of Industrial Hygiene
b. If the forklifts emits a total of 0.37 lb of CO per hour, how long before the TLV is reached for CO? Assume no ventilation.
c. What are the signs and symptoms of CO poisoning? What administrative and engineering controls would you recommend if buying new electric forklifts are not an option?
d. Using the equation (C=G/Q) how much ventilation, in cfm, is required to reduce the concentration to ½ the TLV? Assume steady state room concentration is reached.
e. Given the room volume, how many air changes per hour is this? 6) Suppose you measured vapor exposure in workers operating a paint spray booth
3) Suppose you measured vapor exposure in workers operating a paint spray booth
|
#
|
Solvent
|
TWA (ppm)
|
OEL (ppm)
|
|
1
|
MIBK
|
15
|
50 ppm
|
|
2
|
Toluene
|
27
|
100 ppm
|
|
3
|
Methanol
|
75
|
200 ppm
|
|
4
|
IPA
|
147
|
400 ppm
|
a. Are these workers over exposed to the mixture ?
b. What does this assume regarding the health effects associated with the mixture?
c. How would select gloves to protect against this mixture?
4) Use the data below to answer the following questions regarding asbestos sampling.
|
Sample
|
Fibers/L
|
Minutes
|
|
1
|
626
|
48
|
|
2
|
181
|
67
|
|
3
|
945
|
44
|
|
4
|
575
|
49
|
|
5
|
377
|
32
|
|
6
|
420
|
47
|
|
7
|
191
|
63
|
|
8
|
470
|
22
|
|
9
|
350
|
41
|
|
10
|
1110
|
67
|
a. What is the OSHA methodology for personal sampling of asbestos fibers in air?
b. Calculate the 8-hour TWA for the data above?
c. Is the concentration above the TLV? d. If yes, what type of respirator would assign the worker? Assume there is oil in the air.
e. If the respirator is rated N100, what does that mean? Specifically address the numeric value assigned to the respirator. How is this value determined?
5) Prior to sampling for silica you weighed a filter and recorded the mass (12.836 g). After sampling for 8-hours at 1.68 Lpm, you post-weigh the filter and determine the mass to be 13.112 g.
a. Calculate the concentration of dust in the air?
b. Assume the total silica fraction was 8.3% of the dust collected. Is this above the TLV? # Solvent TWA (ppm) OEL (ppm) 1 MIBK 15 50 ppm 2 Toluene 27 100 ppm 3 Methanol 75 200 ppm 4 IPA 147 400 ppm Sample Fibers/L Minutes 1 626 48 2 181 67 3 945 44 4 575 49 5 377 32 6 420 47 7 191 63 8 470 22 9 350 41 10 1110 67
6) A worker is cleaning a tank (non-confined space) and is exposed to 172 ppm of toluene. The job is expected to take 8 hours to complete
a. Calculate the hazard ratio (use the TLV)
b. Calculate the MUC for each type: ½ mask, full face-piece, powered air purifying respirators with a hood (PAPR)
c. Based on the MUC, which type of respirator would you assign to the worker?
d. How long could the worker be exposed to 172 ppm and not incur breakthrough?
e. Based on the estimated breakthrough time, would you select another type of respirator?