Figure 3  Proportion of total pfu captured by each Andersen stage, by sampling media type. * Stage 6 (0.65 µm to 1.1 µm) omitted from the 27 mL cMEM fill, due to overspill of liquid from the previous (1.1–2.1 µm) stage. n = 4 for 27 mL cMEM and 7ml cMEM, gelatine filter n = 3.