Andersen APS Sample Type MMAD (calc) MMAD GSD 27 mL 1.86 µm 1.59 µm 1.78 to 1.92 7 mL 1.49 µm 1.65 µm 1.84 to 1.92 GF 1.69 µm 1.74 µm 1.78 to 1.91 Average 1.68 µm 1.66 µm 1.85