Male infertility French researchers announced in late May that sitting for long hours behind wheel, could cause infertility in men. Driving a car or truck for hours, they said, raises the temperature of the scrotum and this can lower sperm counts. Men usually produce at least 20 million sperms per millilitre of semen. Anything lower than that is considered impaired fertility. It is estimated that one in 10 couples experience fertility problems. About a third of cases are due to a male problem which normally is due to either the quality or quantity of sperm.