Figure 1: Schematic representation of the effects of tobacco smoking on male fertility. The figure identifies the main hazardous components of tobacco. Tobacco smoking leads to reduced semen quality including semen volume, sperm density, motility, viability, and normal morphology. Furthermore, reproductive hormone system disorders, dysfunction of spermatogenesis, sperm maturation process, and impaired spermatozoa function have also been observed in smokers. The left part of the figure indicates the underlying mechanism. Increased reactive oxygen species level caused by hazardous components of tobacco will lead to DNA fragmentation and apoptosis which will result in the impairment of sperm function leading to lower male fertility.