Advice from Marsh Risk Advisory:
"Corsi Rosenthal boxes are effective in cleaning air inside a classroom."
Any cables that are required to power the fan should be taped to the floor to avoid trips. Other risks include students attempting to touch the spinning fan, but the fans do have covers and this is considerered to be low risk. A study by Underwriters Laboratories (UL) tested box fans with MERV-13 filters attached, finding them to not present a fire hazard even in extreme, modified conditions.