It is imperative that LPs be kept free from foreign matter deposits. Oils from fingerprints, adhesives, and soot are damaging, as are air pollutants like cigarette smoke. Even grease from cooking can deposit itself on LPs. Probably the number one contributor to damage, however, is ordinary household dust. Dust can become embedded permanently into the disc's grooves, causing distortion of the transmitting signal, ticks, pops, and inferior sound quality. Vinyl discs can become so dirty and scratched that they are virtually unlistenable.