Secondhand smoke cause many diseases. The Institute of Medicine of The National Academies had published a book about how secondhand smoke affect health. Here is the summary from the book:
Secondhand smoke, also known as environmental tobacco smoke, is a complex mixture made up of particles and gases and includes smoke from burning cigarettes, cigars, and pipe tobacco (sidestream smoke) and exhaled mainstream smoke. This includes aged smoke that lingers after smoking ceases. Data suggest that exposure to secondhand smoke can result in heart disease in nonsmoking adults. Progress has been made recently in reducing involuntary exposure to secondhand smoke in workplaces, restaurants, and other public places in the United States and abroad, often through legislation that bans smoking. The effect of legislation to ban smoking in public places and workplaces on cardiovascular health of nonsmoking adults, however, remains a question.
You can download the book here:
Secondhand Smoke Exposure and Cardiovascular Effects: Making Sense of the Evidence