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Total suspended particulate matter (TSP) concentration in ambient air is to be measured using a high volume sampler. The filter used for this purpose had an initial dry weight of 9.787 g. The filter was mounted in the sampler and the initial air flow rate through the filter was set at 1.5 m³/min. Sampling continued for 24 hours. The airflow after 24 hours was measured to be 1.4 m³/min. The dry weight of the filter paper after 24 hours sampling was 10.283 g. Assuming a linear decline in the air flow rate during sampling, what is the 24 hours average TSP concentration in the ambient air?
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- 59.2 mg/m³
- 118.6 mg/m³
- 237.5 mg/m³
- 574.4 mg/m³
Correct Option: C
Initial volume of air flow in 1 hour = 1.5 × 60 = 90 m³/h
Volume after 24 hours = 1.4 × 60 = 84 m³/h
Change in weight of filter = 10.283 – 9.787 = 0.496 g 
Volume of air passed in 24 hours = area of the diagram = 1/2 × (90 + 84) × 24 = 2088 m³.
| Average TSP concentration = | ||
| Volume of air passed |
| = | = 237.5 mg/³. | |
| 2088 |
