Engineering controls as an intervention to reduce worker exposure

The implementation of controls to reduce worker exposure should be considered the ultimate goal of any successful industrial hygiene program. The industrial hygiene literature has consistently described a hierarchy of controls, consisting first of the engineering controls (substitution, isolation, ventilation), and followed by administrative controls (personal protective equipment, worker education, scheduling etc.). Recently, exhaust ventilation has been the most popular form of engineering control technology for controlling exposure to airborne contaminants. The use of ventilation to control exposures is not without its problems, however, and many of these problems potentially are more severe in smaller companies. This paper proposes a new emphasis on the first control in the hierarchy, substitution. Historically, substitution has meant the substitution of a hazardous chemical or process by one that is less so. This definition is too restrictive; because of this, it is proposed instead to use the term process change, defined as the use of any process modifications that serve to reduce worker exposure. The advantages and disadvantages of the process change approach are discussed and are illustrated with case studies.