The Control of Toxic Hazards

1. There is a hierarchy of control both in a health-and-safety sense and in a legal sense (i.e., the OSHA law):
  • The best control is at the source (substitution, enclosure, etc.);
  • The next best control is along the path (i.e., ventilation, housekeeping, etc.); and
  • The least effective control is at the worker (i.e., respirators and other personal protective equipment - PPE).

    2. Respirators can only be used:

  • If engineering controls are not technically feasible; or
  • While engineering controls are being installed.

    3. Respirators are a dangerous and unsatisfactory control because:

  • They do not stop exposure but rely on a mask to prevent dangerous exposure;
  • They are hot and uncomfortable to wear; and
  • They have many other limitations. (See Respiratory Protection.)

    4. Local exhaust ventilation is only effective when properly designed for the specific situation. An LEV system's effectiveness and safety is best measured by its captive velocity rating.

    5. Maintenance operations are crucial if prevention of major hazards is to occur. The major issue here is negotiating manpower and time to do the job properly. Housekeeping is also a staffing and labor time issue.

    Summary written by Jerry Roseman, Industrial Hygienist.