Air pollution has long been known to cause a wide range of maladies, from depression to cardiovascular disease.
Now, a new study says there’s another health problem impure air may create: male fertility.
And while the study suggests the overall impact is minor for most individuals, the paper’s author says, in theory, every man on Earth may be effected because each of them is breathing imperfect air.
“It affects everyone, the whole planet,” Dr. Xiang Qian Lao of the Chinese University of Hong Kong told Seeker. “No one can simply stop breathing.”
The new study was the largest of its kind, examining 6,500 men aged 15 to 49 years old in Taiwan, and was published Tuesday online in the journal Occupational & Environmental Medicine.
The researchers looked at the impact of exposure to a certain type of air pollution known as fine particulate matter, or PM2.5. That type of pollution is made up of particles less than 2.5 micrometers in diameter, which can penetrate deep into human lung tissue.
Researchers used local air-quality monitoring stations and satellite data to create a map of exposure to PM2.5 in different areas of Taiwan, then assessed samples of sperm quality for the men in each area. PM2.5 levels were estimated for each man's home address.
The researchers assessed sperm quality by measuring sperm count, shape, size, and movement, using guidelines set out by the World Heath Organization.
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The results suggest a strong association between PM2.5 exposure and abnormal sperm shape, the authors conclude.
In fact, for every 5 micrograms (or, for every five millionths of a gram) per cubic meter of air of fine particulate matter over a 2-year span, the researchers observed a drop in sperm size of 1.3 percent.
While the researchers called the impact relatively small in clinical terms, the widespread nature of the problem indicates it might spell infertility for a “significant number of couples,” the authors conclude.
Exactly how air pollution impairs sperm development remains unclear. But some components of fine particulate matter, such as heavy metals and polycyclic aromatic hydrocarbons, have been linked to sperm damage in experimental studies.
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“Previous studies have been inconsistent,” said Xiang. “Some studies find that there’s a correlation, but some studies do not. Our study finds a robust association.”
Kevin McConway of the Open University in England, a specialist not associated with the study, told AFP: “If I were young enough to worry about my fertility, I wouldn't put moving to an area with cleaner air at the top of my list of actions — though there are certainly many other health-related reasons to live in cleaner air.”
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