Surface barriers reduce the risk of cross contamination caused by airborne aerosols, splash and spatter. The most common surfaces easily protected by surface barriers are: Touch Surfaces: usually contaminated by staff during a procedure. Transfer Surfaces: not touched directly by the dental staff, but usually contacted by contaminated instruments. Splash, Spatter & Aerosol Surfaces: comprise all surfaces in the operatory not classified as touch or transfer surfaces. Examples include dental chairs, x-ray heads, view boxes, unused countertop areas.