Yes, it is really unhealthy

Everyone knows smoking is bad for you, but the effects of second-hand smoke are not as well understood. Sometimes called passive smoking or environmental tobacco smoke, the phenomenon has been extensively analyzed since the 1980s. The results of these studies, which have influenced public smoking legislation around the world, have consistently shown that inhaling second-hand smoke has both long- and short-term detrimental health effects. According to a report released by the US Surgeon General's office in 2006, "Second-hand smoke exposure causes disease and premature death in children and adults who do not smoke... children exposed to second-hand smoke are at an increased risk for sudden infant death syndrome, acute respiratory infections, ear problems, and more severe asthma. Smoking by parents causes respiratory symptoms and slows lung growth in their children." Children and their developing bodies are particularly vulnerable to the effects, especially because those exposed to second-hand smoke tend to have weaker lungs, which in turn makes them more likely to develop other health problems later. The reports states that adult non-smokers who are consistently exposed to second-hand smoke at home or at work increase their risk of developing heart disease by 25-30 percent, and of developing lung cancer by 20-30%. Explaining that there is no risk-free level of exposure to second-hand smoke, the report finds that "eliminating smoking in indoor spaces fully protects non-smokers from exposure to second-hand smoke" but that "separating smokers from non-smokers, cleaning the air, and ventilating buildings cannot eliminate exposures of non-smokers to second-hand smoke." There are immediate, even fatal, consequences from exposure to second-hand smoke as well: It can cause asthma attacks, and also can be the trigger for heart attacks for those already susceptible to them. A study released by the American Heart Association last October analyzed the results of a public smoking ban initiated by the city of Pueblo, Colorado, in 2003. The study found that in the 18 months after the ban took effect, hospital admissions for heart attacks by residents of the city dropped 27 percent, while admission rates for neighboring communities stayed the same. "The decline in the number of heart attack hospitalizations within the first year and a half after the non-smoking ban that was observed in this study is most likely due to a decrease in the effect of secondhand smoke as a triggering factor for heart attacks," said AHA president Raymond Gibbons in a statement. "The ordinance will likely continue to decrease the number of heart attacks and save lives every year."