Occurred in January 2018 / Mead, Colorado, USA
Info from Licensor: "The guy on the ladder was late to work for a week so I told him that he needed to adjust the fan because it wasn't working right. He got his ladder and as he was getting set up I had another guy inside waiting to knock the fan to blow all the dust outside onto the guy on the ladder. When he got up to the fan the guy inside knocked the dust loose and covered the guy on the ladder"