About 0.05 mL of allantoic fluid of fertilized hen’s eggs, in which influenza A/Aichi/2/68 (H3N2) virus was propagated, was atomized inside the patient hood, simulating bioparticles of a patient’s cough using an electric compressor-type nebulizer, which generated mists of 1–10 µm diameter particles (NE-C16; Omron, Kyoto, Japan). Airborne particles were collected from inside and outside of the patient hood using an air sampler and a gelatin membrane filter (MD8 AirScan Sartorius AG, Göttingen, Germany) for virus detection and quantitation, as described previously (11 (link)). A total of 320 L of air was passed through the membrane at a flow rate of 80 L/min (i.e., 4 minutes sampling time). The gel membrane filter was then dissolved in 10 mL of culture medium, Minimal Essential Medium Eagle (Sigma-Aldrich, UK), (37 °C) then subjected to a conventional plaque assay using Madin-Darby canine kidney (MDCK) cells (12 (link)).