Thomas Hawk has a great collection of portraits taken during the 2012 Holi Festival of Colors at Spanish Fork, Utah. Its interesting the contrast between the gas mask which one often associates with war or disaster and the vivid colours.
In Black River Falls the non infected people could be around the infected people but if they were too close to them they could get it. So they used gas mask to be close to the infected people. It was an air born illness so that why they used gas mask.