Men might improve their fertility by reducing how much pollution they breathe in. The dirtier the air, the lower a man's sperm count and the more sperm with fragmented DNA he produces, two new studies suggest.
However, neither report directly links the decline in sperm quality to fertility problems.
"The decrease is not enormous," comments environmental chemist Brian McCarry of McMaster University in Hamilton, Ontario, who was not involved in either study. "There's no evidence that it has an impact on fertility."
In one study, ozone appeared to be a culprit behind diminished sperm counts, suggesting that it's a "sperm toxicant," say Rebecca Z. Sokol of the University of Southern California in Los Angeles and her colleagues. They had looked for a correlation between the quality of semen from 48 local sperm donors and air-quality data for the zip code in which each donor lived. The donors were healthy men who had given 10 or more donations to a sperm bank over at le