High levels of air pollution have recently been associated with poor sperm quality, and could be partially responsible for the drop in male fertility uncovered by a study earlier this year.
This latest study checked the sperm levels and quality of nearly 6,500 men aged between 15 and 49 in Taiwan between 2001 and 2014. Researchers assessed quality and measured the level of fine particulate pollution, and found a correlation between high levels of pollution and low percentage of normal sperm morphology resulting in a higher chance of being in the bottom 10% of normal sperm size and shape. This information took into account other potential factors such as smoking, drinking, age, and weight.
However, some clinicians disagree about the relevance of sperm morphology and overall fertility. Richard Sharpe, Professor at the University of Edinburgh and an expert in male reproductive health, has stated that, “Sperm morphology is highly variable both between men and within the ejaculate of an individual man… so the changes of the order of magnitude reported here in association with exposure to fine particulate matter are unlikely to be of any great relevance to likely fertility.”
Other factors, such as diet and socioeconomic background, may lead to similar or even larger variation which would place air pollution lower down the list of factors that are likely to affect male fertility in the long term.
Fine particulate matter, such as heavy metals and polycyclic aromatic hydrocarbons released by cars and burning wood, has already been associated with sperm damage in previous studies. This study builds upon that existing information and can provide further evidence for researchers trying to pinpoint the reason for the extreme drop in sperm levels in the west over the last 40 years.