It is not enough to be cigarette-free in order to keep yourself away from strokes, according to Harvard School of Public Health researchers. A paper to be published in the September issue of the American Journal of Preventive Medicine found that even when being exposed to secondhand smoke in the home because your spouse is a smoker your risk of stroke significantly increases.

Secondhand smoking has been accepted as a risk factor for coronary heart disease for years but there have been little research done on this association. And with so many smoking bans in public places, the home appears to be the most likely place for nonsmokers to be exposed to secondhand smoke.

According to a study by the Centers for Disease Control and Prevention released earlier this month, about half of the nonsmoking US population still has to inhale cigarettes smoke. The bad news is that many people usually underestimate the gravity of being exposed to secondhand smoke. This type of smoke, carrying numerous dangerous chemicals, is responsible for the increase by at least 20 percent of lung cancer risk and for that of heart disease by about 25 percent.

Secondhand smoke also seriously affects children, as it increases the chance for them to develop asthma and ear problems. Many studies have shown that smoking or being exposed to cigarette smoke during pregnancy can cause your baby sudden infant death syndrome. Related to this specific matter, a report of Bristol University’s Institute of Child Life and Health released in October last year shows that nine out of ten cot deaths babies had mothers who smoked or were exposed to cigarette smoke during their pregnancy. The same report shows that the smoke may affect brain chemicals in the fetus, or could prevent the proper lungs development.

For the current study, M. Maria Glymour, ScD, of the Harvard School of Public Health and colleagues analyzed the smoking habits of the spouses of more than 16,000 stroke-free married adults aged 50 and older who were enrolled in the Health and Retirement Study. The study was funded by the national Institute on Aging and the Robert Wood Johnson Foundation Health and Society Scholars Program.

The participants were followed for about nine years to document the occurrence of first stroke. There were 1,130 first strokes reported during the follow-up period.

The researchers found that being married with a smoker raised the risk of a stroke by 42 percent among those who never smoked. The risk increased in the case of former smokers who were married with a smoker by 72 percent compared with those who were married to a never-smoker.

“These findings indicate that spousal smoking increases stroke risk among nonsmokers and former smokers. The health benefits of quitting smoking likely extend beyond individual smokers to affect their spouses, potentially multiplying the benefits of smoking cessation,” Glymour said.

Smoking is considered one of the major killers globally. According to a report released last year by the World Health Organization, tobacco-related disease will kill 8.3 million billion by 2030 if measures are not taken.

“The only two epidemics that are encountering a major increase in the next 20 years are the tobacco epidemic and the HIV/AIDS epidemics,” Douglas Bettcher, director of the World Health Organization's Tobacco Free Initiative said at the time.