Occupational Safety and Health Administration OSHA

Chemical Hazards and Toxic Substances

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Controlling Exposure

Hierarchy of Controls

The following references aid in controlling workplace hazards associated with chemical hazards and toxic substances.

Overview of Controls

Controlling exposures to chemical hazards and toxic substances is the fundamental method of protecting workers. A hierarchy of controls is used as a means of determining how to implement feasible and effective controls.

OSHA’s longstanding policy is that engineering and work practice controls must be the primary means used to reduce employee exposure to toxic chemicals, as far as feasible, and that respiratory protection is required to be used when engineering or work practice controls are infeasible or while they are being implemented.

Where possible, elimination or substitution is the most desirable followed by engineering controls. Administrative or work practice controls may be appropriate in some cases where engineering controls cannot be implemented or when different procedures are needed after implementation of the new engineering controls. Personal protection equipment is the least desirable but may still be effective.



Type of Control Examples
Engineering Controls (implement physical change to the workplace, which eliminates/reduces the hazard on the job/task)
  • Change process to minimize contact with hazardous chemicals.
  • Isolate or enclose the process.
  • Use of wet methods to reduce generation of dusts or other particulates.
  • General dilution ventilation.
  • Use fume hoods.
Administrative and Work Practice Controls (establish efficient processes or procedures)
  • Rotate job assignments.
  • Adjust work schedules so that workers are not overexposed to a hazardous chemical.
Personal Protective Equipment (use protection to reduce exposure to risk factors)
  • Use chemical protective clothing.
  • Wear respiratory protection. [See the Respiratory Protection Safety and Health Topics page]
  • Use gloves.
  • Wear eye protection.
Additional Information
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