Several studies indicate that human semen quality and fertility have declined over the last decades. According to the estimation of World Health Organization about 8% of couples at the global level experience some forms of infertility problem during their reproductive lives. This percentage means that 50 to 80 million people have problems with fertility. Several lifestyle-related (obesity, smoking) and environmental (exposure to traffic exhaust fumes, dioxins, combustion products) factors appear to negatively affect human fertility, emphasizing the importance of environmental/lifestyle impacts throughout the life course.Support for this work was provided by: Ministry of Education and Science (Spain) (CTQ2008-05520 project); Valencian Community Government (Spain) (PROMETEO/2009/043/FEDER and ACOMP2011/224 projects); Chair Human Fertility of University of Alicante
