Smoking is widely known to harm the lungs, but its impact on the heart and arteries is just as deadly. According to the World Health Organization, tobacco kills more than 8 million people each year worldwide, and many of those fatalities are due to heart disease and stroke. In the United States, smoking now causes roughly one in every four cardiovascular deaths. Smokers face 2 4 times higher risk of a heart attack or stroke than non-smokers. Even "light" smokers aren't safe: CDC studies show that people who smoke fewer than five cigarettes a day often already show early signs of arterial damage.

Dr. Abhijit Borse, sr. Interventional cardiologist at Mumbai's Asian Heart Institute goes on to elaborate further.

Cigarette smoke delivers a toxic cocktail of nicotine, carbon monoxide and thousands of other chemicals into the bloodstream. Nicotine triggers the release of adrenaline, causing immediate spikes in heart rate and blood pressure. At the same time, carbon monoxide from smoke binds to hemoglobin in red blood cells, starving the heart muscle of oxygen (a bit like mild carbon monoxide poisoning). The smoke particles and chemicals irritate and inflame the inner lining of arteries. In CDC studies, smoking "damages cells that line the blood vessels," makes blood more "sticky," and accelerates plaque buildup. Specifically, smokers tend to have higher triglycerides and lower HDL ("good") cholesterol, conditions that promote fatty deposits (atherosclerosis) in artery walls. Over years of smoking, these effects add up: blood vessels thicken and harden, plaque accumulates, and arteries narrow. In short, smoking speeds up the clogging of arteries dramatically raising the odds of a heart attack or stroke.

A crucial finding from recent research is that no amount of smoking is safe for the heart. One analysis of dozens of studies found that even one cigarette per day carries about half the cardiovascular risk of a pack-a-day habit. For example, light daily smoking roughly doubles a woman's heart attack risk compared to a non-smoker (and even men see a large jump in risk with any smoking). Another large review revealed that female smokers may be especially vulnerable: women who smoke had about 25% higher risk of coronary disease than men who smoke the same amount. (Researchers suspect biological factors may play a role in this difference.) Age matters too: smoking tends to make heart disease appear earlier, especially in younger adults. In practical terms, these risks have big effects on public health. Smokers typically develop heart disease decades sooner than non-smokers. (For example, one study found that women age 40 49 who smoke had over eight times the heart disease risk of non-smokers, a risk that actually fell to "only" ~3 times higher by age 70 79.) While precise odds vary by study, the message is clear: cigarette smoke is a powerful cardiovascular toxin, and even occasional smoking significantly raises heart attack and stroke odds.