In many locations around the world, a significant portion of airborne dust is made up of silica (SiO2) in the form of microscopic quartz and sand particles. Silica particles are highly abrasive and are typically harder than the metals and alloys used in the construction of engine pistons, rings and liners. Engine damage occurs when silica particles within a critical size range lodge in the oil film that normally separates the piston ring from the liner bore. The immediate effect is the scratching of the metal surfaces due to the abrasive properties of the particles. As the damage progresses, the metal surfaces fatigue due to the lack of lubrication and eventually begin to degrade and break apart, often leading to significant engine damage or catastrophic failure.