When Rita was growing up in the 1950s, both of her parents smoked. The living room was nearly always filled with bluish-grey clouds, particularly after meals. She and her brother remember choking for breath in the back seat when they took family trips in their Volkswagen.

At university in the 1960s, most students and professors smoked in the classroom. And when she took her first job at a daily newspaper, a cloud of smoke always hovered over the horseshoe-shaped city desk.

Today when Rita fills out health questionnaires, she marks the box “never smoked” but always feels she should add an asterisk.

As they inhale deeply to get every last bit of nicotine, smokers may get annoyed at rules and laws protecting others from their second hand smoke. But passive smoke has been identified as a known cause of cancer and has been linked to heart disease, lung disorders, infections, SIDS and premature death in both children and adults.

A combination of the smoke given off by the burning tip of the cigarette, pipe or cigar and the smoke that’s exhaled, second hand smoke includes more than 100 harmful chemical agents, and they can linger in the air for hours. While smokers get more than 100 times the dose compared to non-smokers, the U.S. Surgeon General has determined that there is no risk-fee level of exposure. Even a small amount of smoke over a short period can be hazardous to health.

The most well known effects of smoking involve the lungs–lung cancer, emphysema, chronic bronchitis, infections and asthma.

Most Americans do not readily associate smoking with heart disease, but studies indicate that the effects of passive smoke on the cardiovascular system are particularly rapid and devastating. The American Lung Association estimates that 46,000 Americans each year die of heart disease attributed to second hand smoke. When Helena, Montana enacted laws forbidding smoking in public places and at work sites, hospital admissions for heart attacks declined by 40 percent. That could be taken as a coincidence were it not for the fact that when enforcement of the ban was reversed by a lawsuit, the number of heart attacks in the community once again started to rise.

As outlined in a comprehensive report published in Circulation, the journal of the American Heart Association [May 24, 2005], the cardiovascular effects of second hand smoke are “on average, 80 percent to 90 percent as large as those from active smoking.”

The details all point to a substantial effect on the heart and blood vessels from as little as 30 minutes exposure.

PLATELET ACTIVATION: The function of blood platelets is to promote clotting–very helpful in stopping the bleeding when you incur a small cut on your skin. Unwanted clotting in blood vessels near the heart, however, is a prime reason for a heart attack.

In one early study, smokers and nonsmokers were exposed at the same time to 20 minutes of second hand smoke. At baseline, smokers had elevated levels of platelet activation, indicating long-term cardiovascular effects. At the end of the experiment, smokers had approximately the same level of platelet activation while nonsmokers experienced increases until they reached nearly the same level as the smokers.

Another study found that repeated 60-minute exposures to smoke increased the baseline platelet activation of non-smokers to a level close to that of smokers.

ENDOTHELIAL FUNCTION: The endothelial layer of an artery is the one in direct contact with blood; it’s crucial to healthy functioning of the blood vessel, causing secretion of nitric oxide when dilation of blood vessels is needed and endothelin when it’s necessary for arteries to constrict.

Abnormal function of the endothelial layer can lead to the buildup of plaque deposits (atherosclerosis) and decreased blood flow.

Environmental smoke has a very immediate effect on endothelial function. With just 30 minutes of smoke exposure–comparable to that in a bar–nonsmokers showed impairments comparable to those of habitual smokers. And the effect of repeated exposure was also to create endothelial dysfunction comparable to that of smokers.

Light and heavy smokers have been found to have similar impairments in nitric oxide production, suggesting that the effect is not dose dependent. Besides being a major factor in coronary artery disease, decreased nitric oxide production is also a common reason for erectile dysfunction.

On the hopeful side, at least partial recovery of endothelial function occurs after exposure to smoke ends–both in passive and active smokers.

CHOLESTEROL: Exposure to second hand smoke is associated with lower levels of HDL (the good cholesterol) in both adults and children. The effect on HDL is greater in males than blacks or females.

Non-smoking women exposed to smoke at work for six hours a day over a six-month period, however, had a 31 percent decrease in HDL, compared to a 33 percent decrease for smoking women in the same environment.

INFLAMMATION: It’s now known that inflammation sets the stage for the buildup of plaque in arteries. And for both adults and children, passive smoking results in higher levels of markers for inflammation such as leukocytes, C-reactive protein and homocysteine.

Passive as well as active smoking also leads to damage of cells from oxidative stress and depletes the body’s stores of antioxidants. Over the short term, antioxidant supplements such as vitamin C may offer some protection; over the long term, it’s doubtful that supplements can reverse the damage since studies have found that antioxidants do not reduce the overall risk of heart disease.

The bottom line is that less than seven hours a week of exposure to second hand smoke increases heart attack risk by 24 percent. Laws restricting public and work place smoking enacted over the past 15 years may seem punitive; in reality, they are protective. Between 1988 and 1991, about 88 percent of non-smokers had detectable blood levels of cotinine (a by-product of nicotine). By 2001-2002, that level had dropped to 43 percent.

Despite the changes, more than 126 million non-smokers continue to be exposed to second hand smoke at home, in vehicles, at work or in public places. According to one estimate, if all work places were made smoke-free by law, the result would be 1,500 fewer heart attacks in the first year and a savings of nearly $49 million in direct medical costs.