Installing a plexiglass shield at the front desk falls under which level of the hierarchy of controls?

Correct answer: B. Engineering controls

• A. PPE — masks, gloves, gowns, eyewear — is the LAST line of defence, protecting the individual rather than removing the hazard.
• B. CORRECT. ENGINEERING CONTROLS are physical modifications to the workplace that isolate people from the hazard without depending on individual behaviour. A plexiglass barrier, a sharps container, a rubber dam, high-volume evacuation, and room ventilation are all engineering controls. They rank third in the hierarchy but are the highest tier that is usually achievable in a dental setting.
• C. ADMINISTRATIVE CONTROLS change how people work: appointment spacing, screening protocols, staff training, work rotation. A barrier is a physical object, not a policy.
• D. ELIMINATION means physically removing the hazard altogether — the most effective control, but rarely feasible in dentistry, where the hazards are intrinsic to the work.

Note: The full hierarchy, most to least effective: Elimination → Substitution → Engineering controls → Administrative controls → PPE.