BEIJING, May 26 (AFP) - China's dingy skies and polluted air have had a marked effect on the quality of Chinese men's sperm, a report said Wednesday. Their overall sperm quality declined by 10 percent between 1981 and 1996, the China Daily quoted a survey from the State Family Planning Commission as saying. Studies were conducted on 10,000 men in 39 major Chinese cities, with those living in highly industrialized areas recording the largest drop in sperm quality, it said. The survey showed that the quality of sperm cells, the amount of sperm and the number of living sperm cells had dropped by 10.3, 18.6 and 10.4 percent respectively over the 15-year period.  