Air contamination is bad for our health, that is clear: it causes an array of respiratory diseases, from asthma to lung cancer, if chronic. But a new research published in the "Proceedings of the National Academy of Sciences" shows it may hit where men are most hurt: their fertility.

Mice living in areas with polluted air displayed significant higher levels of gene mutations in their sperm, than mice inhabiting zones with filtered air, a discovery pointing to the fact that airborne contaminants could be causing inheritable DNA alterations.
Rodents exposed to unfiltered air downwind of two steel mills and a major highway in the city of Hamilton, Ontario province (Canada), presented 60% more mutations in their sperm cells than male mice kept in chambers where the air was cleaned with high-efficiency HEPA filters.

Two sets of mice were placed in the contaminated areas, one was exposed to the ambient air, while the other group was placed in the chamber with filtered ambient air.

The individuals' sperm was investigated at 3 weeks and 10 weeks, and while the rate of mutations was high in the sperm of the exposed mice, these damages were fixed following 6 weeks of recovery in the lab.

But when the team focused on a chromosomal location known for its high speed of DNA damage (called "tandem repeat" mutations), they discovered a much increased rate of sperm DNA damage.

The investigated sperm appeared as stem cells during the exposure period, and in natural conditions sperm is strongly protected against this type of DNA damage. This means that a factor in the polluted air affected the DNA of the mouse sperm stem cells.

"These findings show that chemical pollutants may cause heritable mutation. Further research is required to confirm these results, and to evaluate the potential risk to humans exposed to particulate air pollution," wrote the authors.