Efficient hazard control methods in an occupational environment are discussed. The basic principles consist of substitution, isolation, and ventilation. Substitution of less hazardous materials or process equipment may be the most positive method of controlling an occupational hazard. The more closely a process approaches being continuous, the less hazardous that process is likely to be. One of the main requirements for efficient equipment substitution is the awareness of alternates. After equipment substitution, material substitution is the technique most often used to reduce or to eliminate hazards. Isolation techniques for stored materials usually consist of a physical barrier. The best storage technique uses both isolation and ventilation. Hazardous equipment should be isolated from the occupational environment. Process isolation is usually thought to be the most expensive of the isolation methods for hazard control. Personal protective equipment exemplifies the principle of isolating workers from their occupational environment. Ventilation systems can be either local or general. Local exhaust ventilation systems enclose the process or equipment as much as possible. They withdraw air from the enclosure at a rate sufficient to assure that the direction of air movement is always into the enclosure. Problems associated with local exhaust systems are poor design, inadequate exhaust, and inadequate supply. General exhaust and supply systems attempt to control the occupational environment by dilution. All people involved in the occupational environment (management, engineers, supervisors, and workers) should be educated in hazard control.
The Industrial Environment - Its Evaluation and Control, NIOSH, U.S. Department of Health, Education and Welfare