Figure 1. Bioaerosol generation by raindrops.

(a–d) Aerosols generated by drop impingement on a reference surface, which maximized the aerosol generation (a TLC plate (TLC-C) in Table 1). The TLC plates served as an ideal soil-like surface. The white lines are the trajectories of aerosols ejected from the initial droplet after impact over a period of 400 ms. Due to air flow above the droplet, the trajectories of the ejected aerosols are curved. The scale bars indicate 1 mm. For more details, see Supplementary Movie 1. (e) Schematic illustration of the experimental procedure for drop impingement on soil and aerosol collection. (f) Confocal microscopy images of C. glutamicum on the surface of clay soil with the cell density of 250 cells mm⁻². (g,h) Fluorescent microscopy images of aerosols generated by drop impingement on clay soil pre-permeated with C. glutamicum. The red circles and the yellow dots indicate aerosols and C. glutamicum, respectively. The scale bars indicate 200, 50 and 25 μm in f–h, respectively.