A study in the United States shows that second-hand smoke is far more harmful to non-smokers than smokers themselves. While smokers damage their cardiovascular system, the system can adjust itself to counteract some of the consequences of smoking, while the bodies of non-smokers can not adapt to the changes after smoke inhalation. 
Smokers and non-smokers are married, and the latter have a 30% higher risk of dying from heart disease
 the impact of passive smoking on non-smokers is far greater than on smokers.