According to a new research, done one a huge men population, which evaluated more than 14,000 sperm samples, found that ozone can adversely affect a man's sperm, reducing their numbers as well as their crucial ability to move or "swim,".
"Our most significant finding was that as the ozone level went up, the sperm concentration went down," said Dr. Rebecca Z. Sokol, a professor of medicine and obstetrics and gynecology at the University of Southern California's Keck School of Medicine. Sokol presented her findings here Friday at a meeting of the Pacific Coast Reproductive Society.
Sokol's team evaluated 7,021 samples from 40 sperm donors in the Los Angeles area over a 2-year period from 1995 to 1998 and compared them with 5,000 samples donated by 30 men from Northern California during the same time period. The donors' average age was about 20, and most were college students. The researchers also analyzed data on air quality in both regions.
The greater the increase in ground level ozone--popularly known as smog--the greater the drop in sperm counts, the investigators found. Ozone occurs in two layers in the atmosphere--at ground level, where it is an air pollutant that can damage human health, and far up in the stratosphere, where it helps shield the Earth from harmful ultraviolet radiation.
According to Sokol, in these very fertile young men, the drop did not make much of a difference. Their average counts were 80 million sperm per cubic centimeter. But in less fertile men, it could matter more. A sperm count of less than 10 million is considered low and less than 20 million is considered worrisome by fertility experts if a man is trying to impregnate a partner.
Sokol believes her team's study is the first US investigation to examine the relationship between air quality and sperm quality. "I don't think this study suggests in any way, shape or form that being exposed to ozone makes you infertile." "It just suggests that exposure to air pollution is not good for sperm."
It's not the ozone, per se, that is causing the damage, Sokol added. Ozone, once inhaled, is rapidly metabolized. Ozone may trigger an inflammatory reaction, she speculates, which in turn adversely affects the sperm.
According to Dr. Larry Lipshulz, a professor of urology and chief of the division of male reproductive medicine and surgery at Baylor College of Medicine in Houston., the data is far too preliminary to make any far-reaching conclusions. He added that it's important to look at an environment with low ozone to see if there's no effect (on sperm).