Most of us think that there's no need to worry if you are standing in a group of smokers although you do not smoke. However that is not the case. Second-hand smoke also known as passive smoking can be more dangerous than active smoking. Dr Duru Shah Director Gynaecworld Center for Assisted Reproduction & Women s health Mumbai explains in detail why it is so. Second-hand smoke is a mixture of sidestream and mainstream smoke. The smoke which comes from the burning end of a cigarette is termed as sidestream smoke and the smoke that is exhaled by the smoker