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Secondhand smoke: Unsafe in any amount

Smoking, first fingered as a prime cause of lung cancer, also contributes to heart disease. Compared with nonsmokers, smokers have double the chances of having a heart attack or stroke. Doctors all agree that if you are a smoker, you are increasing your risk of having heart disease.

About 20 years ago, evidence surfaced that nonsmokers were at risk from being exposed secondhand to someone else's cigarette smoke. At first, a lot of doctors were skeptical that simply inhaling smoke from someone else's cigarette—such as on an airplane or in a restaurant, or at home with a smoking spouse—could really injure the health of a nonsmoker. However, there is now very strong evidence that it can.

Nevertheless, there is still an acrimonious and politically charged debate about secondhand smoke, particularly from owners of businesses such as restaurants and bars who think their business is threatened by no-smoking laws. They cite studies that do not show negative health effects from secondhand smoke. However, most health professionals have come to agree that there is now strong evidence that secondhand smoke is bad for us.

In the city of Helena , Montana , a law that banned smoking in restaurants, bars, offices, and other public venues was in place for six months before a judge overturned it. During the ban, the number of people seen for heart attacks at the only cardiac care hospital for miles was only half of what it had been before the law was enacted and after it had been struck down.

Writing in the April 24, 2004 British Medical Journal, the local cardiologists who carried out the widely publicized study acknowledged the study's limitations. These include Helena 's small size and lack of knowledge about heart attack victims' exposure to secondhand smoke. That said, they conclude that the establishment of smoke-free public places could have a quick and beneficial effect on heart disease.

Blood levels of cotinine (KOE-tin-een), a substance formed when the body breaks down nicotine, are one way to measure exposure to smoke. A team of British researchers looked at cotinine levels in more than 2,000 men who said they didn't smoke to gauge the impact of secondhand smoke.

Cotinine levels were closely linked with exposure to secondhand smoke and to heart disease. After 20 years of follow-up, 18% of the men with the highest cotinine levels had developed heart disease — the same percentage as light smokers — compared to 10% of those with the lowest levels.

Cigarette smoke contains more than 4,000 substances. Nicotine, one of the best known, is the prime addictive element. Other substances in cigarette smoke generate free radicals—natural chemicals that stimulate atherosclerosis in the body's arteries. Cigarette smoke also revs up inflammation, another process at the root of heart disease.

One of the mysteries of secondhand smoke is how it can cause nearly the same level of damage as smoking. There is evidence that, in nonsmokers, exposure to secondhand smoke restricts the ability of coronary arteries to widen and carry more blood when stressed.

Secondhand smoke also makes blood more likely to clot. The combination of arteries that have trouble in widening and an increased tendency to form blood clots creates a double whammy that could trigger a heart attack, especially in nonsmokers who already have heart disease.

The Centers for Disease Control and Prevention (CDC) estimates that secondhand smoke is responsible for 35,000 deaths a year. It's a special risk for people who work in smoke-filled rooms, like waitresses and bartenders. In fact, the CDC now urges people with heart disease or at high risk for it to stay away from indoor settings where smoking is allowed.

If you smoke, you need to know that your habit directly affects the health of others. If you don't smoke, don't hesitate to ask a smoker to "take it outside," especially if you have heart disease. The evidence is that secondhand smoke is more than just a nuisance — it's also bad for you.

November 2004 Update

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