Crankcase ventilation filters reduce blow-by, which is generated by combustion gases leaking past piston rings, producing oil droplets that would otherwise be included in vehicle emissions. These oil droplets are extremely small and can be classified as a drip or an aerosol, ranging in size from 3 microns down to 0.2 microns. As worldwide emissions standards continue to evolve to protect the environment, crankcase ventilation filtration systems are becoming more critical to reducing total engine emissions.