While mild symptoms include eye and throat irritation, exposure to secondhand smoke is responsible for more than 3,000 deaths in the United States yearly, according to the Environmental Protection Agency. Big tobacco continues to dispute the EPA numbers and how second-hand smoking causes serious disease.

Passive smoke, secondhand smoke, environmental tobacco smoke and involuntary smoking all describe a mixture of more than 3,000 chemicals emitted from the burning end of a cigarette and exhaled by active smokers.

Living or Working With a Smoker

A recent study in the Journal of the American Medical Association found that women married to smokers were 30 percent more likely to develop lung cancer than those married to nonsmokers. Women who were exposed to smokers in the workplace had a 39 percent increased risk of developing lung cancer, the study found.

There is also recent evidence that secondhand smoke has a causal link to heart disease, the No. 1 killer of women.

But according to JAMA, women living with smokers are not the only ones at high risk. At bars and restaurants, for example, cigarette smoke is in the air. According to the journal, women in the study exposed to as little as two hours a week for over six months had a 50 percent greater risk of developing lung cancer than non-exposed women.

Perhaps the most vulnerable — and involuntary — secondhand smokers are children, whether inside the womb, as infants or older. Estimates indicate that babies have a fivefold greater risk of falling victim to sudden infant death syndrome if their mothers smoke.

Paternal and maternal smoking is associated with low infant birth weight, respiratory tract infections, reduced lung functioning, buildup of fluid in the middle ear and the development or exacerbation of asthma.

Women who were exposed to smoke both as a child and an adult have nearly twice the risk of developing lung cancer than women exposed only as adults.

Restricting Smoking in Public Places

As evidence of the dangers of secondhand smoke comes to light, many states are facing pressure to restrict smoking in public places. And as no-smoking signs crop up, lung cancer rates are starting to come down, according to Virginia Ernster, vice chairwoman of the epidemiology and biostatistics department at the University of California-San Francisco. California's anti-smoking laws are among the country's most restrictive.

"We've seen a decline in smoking prevalence in California that is greater than the rest of the nation," says Ernster. "As a result, we are beginning to see lung cancer rates decline, whereas they are plateauing in other states."

Although efforts to ban smoking in public places are still in their infant stages in many states, public health experts agree that the only way to avoid the dangers of tobacco smoke is to reduce exposure to it.

Kavita Mariwalla, a second-year medical student at Yale University School of Medicine, contributed to this report.