This U.S. industry comprises establishments primarily engaged in 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. Manufacturing air-conditioning units (except motor vehicle)--are classified in U.S. Industry 333415, Air-Conditioning and Warm Air Heating Equipment and Commercial and Industrial Refrigeration Equipment Manufacturing; Manufacturing motor vehicle air-conditioning systems and compressors--are classified in U.S. Industry 336391, Motor Vehicle Air-Conditioning Manufacturing; Manufacturing household-type fans (except attic) and portable air purification equipment--are classified in U.S. Industry 335211, Electric Housewares and Household Fan Manufacturing; and Manufacturing industrial and commercial blowers, industrial and commercial exhaust and ventilating fans, and attic fans--are classified in U.S. Industry 333412, Industrial and Commercial Fan and Blower Manufacturing.