**2. Semen quality health**

There is ample evidence in the world that global sperm quality has declined over the past few decades [2]. The probable cause of global decreased semen quality may be environmental and / or occupational and lifestyle factors [3, 4]. Lifestyle factors associated with male infertility include: smoking, alcohol consumption, recreational drugs, stress, obesity, paternal age, diet, and coffee consumption. Other factors include: testicular heat stress, cycling, lack of sleep, and cell phone magnetic waves [5].

### **2.1 Smoking**

Research has reported that sperm concentrations in men who smoke are 17–13% lower than in men who do not smoke [6]. In addition, smoking has a negative relationship with sperm motility, sperm morphology and sperm count. Decreased semen quality is more common in men who smoke more than 20 cigarettes a day, or on average 10–20 cigarettes a day, than in men who smoke 1–10 cigarettes a day. The effect size is larger in infertile men than in the general population [7]. In addition to the detrimental effect on male fertility, smoking is responsible for DNA damage, aneuploidy and mutations in sperm [8].
