Question: A series of full-period consecutive dust samples are collected during an 8-hour work shift. Samples were collected on filters and weighed gravimetrically, with results as follow:
| Sample no: |
Flowrate |
Sample Duration |
Mass Collected |
|
(liters per min) |
(min) |
(micrograms) |
| 1 |
2 |
60 |
110 |
| 2 |
2 |
120 |
745 |
| 3 |
2 |
90 |
350 |
| 4 |
2 |
120 |
700 |
| 5 |
2 |
90 |
255 |
What is the 8 hour TWA concentration in milligrams per cubic meter (mg/m
3)?
Think very carefully how you might do this. The final units are in mg/m
3. You have mass in ug. You also have minutes and liters per minute. That should tell you how many liters of air were sampled. Airborne concentration is in mass per volume of air. You can calculate ug/l. Convert to mg/m3 and then calculate the 8 hour TWA (show all work).