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The goal of a hazard prevention and control program is to make the workplace foolproof, to the extent feasible. It is an ongoing program, never finished. You will design and implement and then revise and improve preventive measures and controls as your worksite changes and as your store of hazard information grows.


To the extent feasible, the work environment and the job itself should be designed to eliminate or reduce exposure to hazards based on the following principles:

  1. If feasible, design the facility, equipment, or process to remove the hazard and/or substitute something that is not hazardous or is less hazardous.

  2. If removal is not feasible, enclose the hazard to prevent exposure in normal operations.

  3. Where complete enclosure is not feasible, establish barriers or local ventilation to reduce exposure to the hazard in normal operations.

The most frequent sources for updating hazard information are routine inspections, employee reports of hazards, and accident/incident investigations. Other good sources for hazard information updates are the ongoing job hazard analyses, process and phase hazard analyses, change analyses, and periodic comprehensive hazard surveys.

Engineering controls, which attempt to eliminate hazards, do not necessarily require that an engineer design the control. Engineering controls can be very simple.

Elimination of hazards through design

Some examples of designing facilities, equipment, or processes so that the hazard is no longer present are:

  • Redesigning, changing, or substituting equipment to remove the source of excessive temperature, noise, or pressure;
  • Redesigning a process to use less toxic chemicals;
  • Redesigning a workstation to relieve physical stress and remove ergonomic hazards; and
  • Designing general ventilation with sufficient fresh outdoor air to improve indoor air quality and generally to provide a safe, healthful atmosphere.

Enclosure of hazards

When you can not remove a hazard and cannot replace it with a less hazardous alternative, the next best control is enclosure. While this may control employee exposure during production, it may not control exposures during maintenance. Some examples of enclosure designs are:

  • Complete enclosure of moving parts of machinery;
  • Complete containment of toxic liquids or gasses from the beginning of the process using or producing them to detoxification, safe packing for shipment, or safe disposal of toxic waste products;
  • Glove box operations to enclose work with dangerous micro-organisms, radio nuclides, or toxic substances; and
  • Complete containment of noise, heat, or pressure.

Barriers or local ventilation

When the potential hazard cannot be removed, replaced, or enclosed, the next best approach is a barrier to exposure, or, in the case of air contaminants, local exhaust ventilation to remove the air contaminant from the workplace. This engineered control involves potential exposure to the worker even in normal operations, consequently, it should be used only in conjunction with other types of controls, such as safe work practices designed specifically for the site condition and/or personal protective equipment. Examples include:

  • Ventilation hoods in laboratory work;
  • Machine guarding, including electronic barriers;
  • Duct away chemicals and noise; and
  • Baffles used as noise-absorbing barriers.

Administrative controls

Administrative controls include lengthened rest breaks, additional relief workers, exercise breaks to vary body motions, and rotating workers through different jobs to reduce stress or repetitive motions on one part of the body. They normally are used in conjunction with other controls that more directly prevent or control exposure to hazards.

Personal protective equipment

When exposure to hazards cannot be engineered completely out of normal operations or maintenance work, and when safe work practices cannot provide sufficient additional protection, a further method of control is using protective clothing or equipment. These include face shields, steel-toed shoes, hard hats, respirators, hearing protection, gloves and safety glasses.

Contractor-created hazards

OSHA has learned from accident investigations that all too often contractor actions have caused, or have been contributing causes of, large catastrophic accidents. To assure that contractors do not become a safety liability to a site, perform a thorough evaluation of their safety record and OSHA citation history should be performed during all contract evaluations with specific safety expectations built into the contract. This will allow for removing a contractor should it become necessary. Once selected, all contractors need to receive a thorough site briefing. If the contractors' safety and health program is deficient in any areas then they should be required to make modifications or adopt the site's program before starting work. You can not afford to have two sets of rules on a site, one for the site employees and one for the contractors. All contractors need to understand the seriousness of your safety and health program and that failure to comply with its requirements will be dealt with quickly and appropriately to include cancellation of the contract.