Did you know that as soon as 20 minutes of having your last cigarette, your heart rate and blood pressure (revved by the nicotine in tobacco) start to drop. By 12 hours, toxic carbon monoxide, or CO, in your blood from the cigarette smoke decreases and oxygen levels increase, improving cell health and circulation. Just a 1% rise in carbon monoxide in your blood ups your risk of tobacco-related death by 22%. Lung function improves in about 2 weeks after quitting. Within 5 to 10 years, the risk of dying from respiratory disease is cut by 18%; from lung cancer by 21%. A 2005 study showed that even those with mild lung disease, quitters had a 46% lower death rate over 14.5 years compared to those who kept smoking. American Lung Assocation.