Table 1. Hierarchy of control measures for airborne contaminants in the work environment in order of priority (top to bottom) and in order of preference (left to right)

Control measure	Agent	Process/appliance	Working environment	Work practice
Elimination	Total substitution	Different process	Layout change	Automation, robotisation, remote control
Reduction	Partial substitution, change of form	Adjustment, preventive maintenance, specialised appliance	Good housekeeping	Correct work procedures, training, instruction, motivation, supervision
Isolation		Enclosure segregation	Glove box, safety cabinet, segregation, high-exposure departments	Ensuring enclosure
Ventilation		Local exhaust ventilation, push/pull ventilation	Dilution ventilation, air douches, air curtains	Portable jets, low-volume, high-velocity tools
Exposure avoidance			Booths for operators	Shorter shifts, fewer people, work schedules
Personal protection				Respiratory protection, gloves, clothing