Skip directly to search Skip directly to A to Z list Skip directly to navigation Skip directly to site content Skip directly to page options
CDC Home


NIOSH researchers help prevent occupational disease and injury by conducting workplace engineering evaluations and developing practical, solutions-oriented control technology interventions. To conduct these efforts, NIOSH scientists and engineers work collaboratively with companies, unions, trade associations, labor organizations, universities, and local, state and federal governments, both in the United States and around the world.

The NIOSH Engineering Controls Program Portfolio gives an overview of the entire program.

Two Workers Jack-Hammering

Hierarchy of Controls

Controlling exposures to occupational hazards is the fundamental method of protecting workers. Traditionally, a hierarchy of controls has been used as a means of determining how to implement feasible and effective controls. One representation of this hierarchy can be summarized as follows:

  • Elimination
  • Substitution
  • Engineering controls
  • Administrative controls
  • Personal protective equipment

The idea behind this hierarchy is that the control methods at the top of the list are potentially more effective and protective than those at the bottom. Following the hierarchy normally leads to the implementation of inherently safer systems, ones where the risk of illness or injury has been substantially reduced.

Elimination and substitution, while most effective at reducing hazards, also tend to be the most difficult to implement in an existing process. If the process is still at the design or development stage, elimination and substitution of hazards may be inexpensive and simple to implement. For an existing process, major changes in equipment and procedures may be required to eliminate or substitute for a hazard.

Administrative controls and personal protective equipment are frequently used with existing processes where hazards are not particularly well controlled. Administrative controls and personal protective equipment programs may be relatively inexpensive to establish but, over the long term, can be very costly to sustain. These methods for protecting workers have also proven to be less effective than other measures, requiring significant effort by the affected workers.

Engineering controls are used to remove a hazard or place a barrier between the worker and the hazard. Well-designed engineering controls can be highly effective in protecting workers and will typically be independent of worker interactions to provide this high level of protection. The initial cost of engineering controls can be higher than the cost of administrative controls or personal protective equipment, but over the longer term, operating costs are frequently lower, and in some instances, can provide a cost savings in other areas of the process.


A searchable bibliographic database of occupational safety and health publications, documents, grant reports, and journal articles supported in whole or in part by NIOSH.

Selected Query Results:

Survey Reports

NIOSH conducts engineering evaluation studies as a part of control technology research. The field study portion of this research is documented in workplace survey reports.

Workplace Solutions

Workplace Solutions documents are a series of easy-to-understand, easy-to-access, and easy-to-use recommendations that turn the results of NIOSH control technology research into occupational safety and health practice.

Man Jack-Hammering

Engineering Education (Project SHAPE)

Project SHAPE (Safety and Health Awareness for Preventive Engineering) was a collaborative project between NIOSH, engineering professional societies, and engineering schools to enhance the education of engineering students in occupational safety and health.

Electronic Library for Construction Safety and Health – CPWR/NIOSH (eLCOSH)

The Electronic Library for Construction Safety and Health (eLCOSH) provides a wide range of materials on construction safety and health in English, Spanish, and other languages. eLCOSH is maintained by the Center to Protect Workers' Rights under a grant from NIOSH.

Contact Us:
  • Page last reviewed: December 8, 2011
  • Page last updated: June 25, 2010 The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Rd. Atlanta, GA 30329-4027, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC-INFO