Every single day the human body produces 5 billion skin cells! As our skin cells renew, the old surface cells become hard and dry and eventually fall off to let the new cells shine through. The body also rids itself of contaminated or pollution filled cells in this fashion. For many individuals, especially those who smoke, have acne or are over 40, this process does not happen fast enough and you have what we call " clingers-on", cells that don't seem to know when their time is up.