Figure 1.

Simulation of a cloud of airborne bacteria-containing macro-drops and micro-droplets to quantify barrier potential of household textiles. (A) Graphical overview of the spray model. Inset, Photograph of a human sneeze, public domain, James Gathany, CDC image ID11162). (B) Photographs of short and long-range visible droplets immediately after spray. Note the color, number, size, and relative location and distribution of the bacteria colonies growing from “invisible” microdroplets (CFU) shown as whitish spots on the agar surface. Bacterial growth alters the red color of the fresh non-inoculated agar leading to a brownish discoloring of the petri agars, which is more pronounced as the number of bacterial colonies increase. (C) Number of macro-drops for four simulations over distance. The overall linear equation that best describes the mean spray macro-droplet dynamics linearized/depicted as the heatmap is y = −8E⁻⁰⁵x³ + 0.0305x² – 3.9405x + 198.42, with an R² = 0.9829. Note that large drops of liquids observed with the spray alone (no textile barrier) were not observed with any of the textile barriers tested. (D) Photographs of bacterial CFUs on agar plates illustrating ability of cloud micro-droplets to move around spaces driven by cloud turbulence (left images, agar plates were partially covered with lid at moment of spray), concurrent contamination with macro- and micro-droplets. (E) Number of CFU/plate (56.75 cm²) for 6 simulations over distance. The overall linear equation that best describes the mean dispersal of bacteria-carrying micro-droplets over distance, also depicted as the red heatmap, is y = −4E⁻⁰⁵x⁴ + 0.0177x³ – 2.8522x² + 155.63x – 58.504, with an R² = 0.9994.