It's hard to believe that a little over 50 years ago advertisements in which doctors recommended cigarette brands such as Camel and Lucky Strike ran in popular magazines. Nowadays, even smokers realize how harmful smoking is to their health. The statistics are quite clear: Each year, smoking is responsible for 440,000 deaths in the U.S. and 5 million worldwide. It kills more people than HIV/AIDS, tuberculosis, and malaria combined according to the American Lung Association, and the Surgeon General claims it is the leading cause of preventable death.

Recently, smoking has made the headlines because of its connection to chronic obstructive pulmonary disease (COPD), an umbrella term used for medical conditions such as emphysema, chronic bronchitis, and refractory asthma, among others. In one study, published in mid-March in the journal Respiratory Research, scientists concluded that smokers who had a certain gene variation were more likely to develop COPD [1] ; another study, published in the Canadian Medical Association Journal in April, found that people who smoke both marijuana and cigarettes are three times as likely to develop COPD. [2] Not surprisingly, COPD and smoking are both linked to heart disease, so let's explore what smoking does to the pulmonary and cardiovascular systems and how COPD can contribute to heart disease.

•What smoking does to your lungs: Cigarette smoke contains more than 4,000 chemicals, at least 60 of which are carcinogens. These chemicals render the lungs less flexible, predisposing them to emphesyma, and damage the cilia, hairlike projections that line the airway and are responsible for clearing the respiratory system of irritants. The smoke also causes the lungs to produce more mucus, which makes them more susceptible to chronic infections. It's no wonder then that 80 to 90 percent of people with COPD are smokers...

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