Following our previous work on the visualization of aerosols in July, DNW has participated in an episode of the Topdoks TV programme that aimed to show the effectiveness of different mouth masks. Rachel, one of the two presenters, tried on different types of mouth masks and coughed in them to test their particle retention. DNW’s expertise in flow visualization was applied to make particles expelled while coughing visible. The set-up installed by DNW consisted of UV lights and filters for the cameras. The post-processing of images was also carried out by DNW. The full episode can be viewed here, starting at minute 8:40 (in Dutch).