Over the temperature and concentration range examined, no change in the collection efficiency was observed. Collection efficiency dropped to 90% at a sampling rate of 3 L/min. When using much higher sampling rates, e.g. 12 L/min, in conjunction with a 47 mm diameter silica-fiber, and two 250 mL capacity impingers in series, each containing 150 mL of 3% H2O2, a collection efficiency 98% of SO2 was obtained (9).