Official definition

This U.S. industry comprises establishments primarily engaged in (1) manufacturing stationary air purification equipment, such as industrial dust and fume collection equipment, electrostatic precipitation equipment, warm air furnace filters, air washers, and other dust collection equipment, and/or (2) manufacturing attic fans and industrial and commercial fans and blowers, such as commercial exhaust fans and commercial ventilating fans. Cross-References. Establishments primarily engaged in--