When hazards are identified, it is useful to consider general principles of control, which can be thought of as two basic categories: "pre-contact" or "point-of-contact."
Pre-contact control is the first and most important method because it prevents the hazard from reaching the worker. Pre-contact control methods include substituting materials or processes that are less hazardous, isolating hazardous processes, retrofitting existing equipment, or acquiring safer equipment. Pre-contact control can also be achieved by providing protection to the worker with local exhaust ventilation, machine guarding, better housekeeping, and safe work practices. Many Canadian jurisdictions legislate pre-contact controls. While many hazards can be anticipated and avoided through effective engineering at the pre-contact stage, others may not be recognized before an accident occurs. A thorough effort to identify hazards is essential so that hazards may be reduced or eliminated at the source.
Where pre-contact controls are not practical, feasible, or totally effective then point-of-contact controls must be used.
The point-of-contact control is important but secondary because it cannot eliminate the hazard. It only manages the hazard at the point of contact with the worker. This form of control is primarily accomplished through personal protective equipment. It is to be used when pre-contact controls are not totally effective.