Your lungs have a nearly miraculous ability to heal themselves. Although longtime smokers will always have an increased risk of lung cancer, kicking the habit brings immediate health benefits. Here are some benefits the average smoker can expect from quitting:
• After 8 smoke-free hours, your blood’s carbon-monoxide and oxygen levels return to normal. This change can reduce fatigue and headaches, and increase your ability to exercise.
• After 1 smoke-free day, your chance of having a heart attack has already declined.
• After 2 or 3 smoke-free weeks, your lung function improves by nearly a third.
• After several smoke-free months, new and healthy cilia (the tiny lung-cleaning hairs) begin to grow, increasing your ability to clean your airways and prevent infection.
• After 1 smoke-free year, your risk of heart disease is half that of a continuing smoker.
Source of Information : Oreilly - Your Body Missing Manual