The following information comes from a study conducted by the Federal Center for Disease Control and Prevention:
Within 20 minutes your blood pressure and pulse rate drop to normal. The body temperature of your hands and feet increase to normal.
Within 8 hours the carbon monoxide level in your blood drops to normal and the oxygen levels in your blood rise to normal. Your smoker's breath disappears.
Within 24 hours your chance of a heart attack decreases
Within 48 hours your nerve endings start regrowing. The ability to taste and smell are enhanced.
Within three days you breathe easier.
Within two weeks to three months your circulation improves and walking becomes easier. Your lung function increases up to 30 percent.
Within one to nine months you cough less and your sinus congestion and shortness of breath decrease. The cilia that sweep debris from your lungs grow back. You feel more energetic.
Within one year your excess risk of coronary heart disease is half that of a smoker.
Within two years your heart attack risk drops to near normal.
Within five years the lung cancer death rate for the average former smoker (one pack a day) decreases by almost half.
Within ten years your lung cancer death rate is similar to that of a non-smoker. All of your pre-cancerous cells are replaced. Your risk of cancer of the mouth, throat, esophagus, bladder, kidney and pancreas decreases even more.