Air pollution can damage sperm, reducing the chances of conception and raising the risk of miscarriage, say researchers based in the Czech Republic. The study, published in the journal Human Reproduction, also shows that a man's sperm quality will improve again if pollution levels drop. The findings show that the effects of air pollution on sperm are temporary, suggesting that it affects mature sperm late in their development, say the scientists.

The team studied men living in Teplice, a town in the Czech Republic that has high levels of air pollution during the winter months. They monitored 35 men for two years, and found that their sperm quality deteriorated during the winter, and improved significantly during the months when air quality improved.

UK expert Dr Allan Pacey, secretary of the British Fertility Society, commented that 'we are uncovering more and more evidence that sperm DNA can be damaged by a variety of environmental or occupational factors'. He said that the new study provides 'the first real evidence that air pollution can damage sperm DNA', but added it was 'reassuring' that the effect appears to be reversible. He cautioned that men trying to conceive should be aware of what might damage their sperm, and should try and avoid chemicals at home and at work. However, he also said that men should remember 'it takes about three months to produce sperm so any change they make will take that time to be effective'.

In 2003, Italian scientists showed that road traffic fumes may affect male fertility. Scientists from the University of Naples looked at young and middle-aged male attendants at motorway toll stations, and found decreased sperm quality. However, pollution is just one of many factors that can affect sperm and male fertility. The authors of the latest study make a number of recommendations to help men produce the 'best quality sperm possible' - eat healthily, do moderate exercise, stop smoking, reduce alcohol intake, and avoid pollution, marijuana and situations that increase the temperature of the testicles.

Reproduced from BioNews with permission, a web- and email-based source of news, information and comment on assisted reproduction and human genetics, published by Progress Educational Trust.