Tobacco smoke contains a mix of more than 7,000 chemicals. Out of these, hundreds are dangerous to humans, while about 70 can cause cancer.
Once a person stops smoking, the effects starts immediately. Heart rate begins to go back on it's normal level within 20 minutes after the last smoked cigarette. Not smoking for 2 hours can lead to better blood circulation that keeps the blood pressure and heart rate normal. The amount of oxygen in the blood increases to its normal level because the carbon monoxide produced from smoking decreases as early as 12 hours after quitting.
The risk of a heart attack in a smoker is 70% higher than a non-smoker. This risk slowly decreases about 24 hours after the person quits. This risk is lowered by half after a year of not smoking.
Nerve endings have special role in our sense of taste and smell. These nerve endings are weakened when exposed to nicotine- the addictive ingredient of tobacco. After 48 hours of quitting, the nerve endings begin to regrow, improving the sense of smell and taste. The lungs also start to repair between one to nine months after not smoking.
People who quit by the age of 30 increase their life expectancy by 10 years because the risk of developing smoking-related diseases are decreased. While people who quit by the age of 60 years can still add three years to their life.