A new research has found evidence of air pollution causing poor sperm motility in men living in China.
Approximately 48 to 186 million reproductive-aged couples worldwide suffer from infertility. According to the World Health Organization (WHO), male factors account for 50% of global infertility cases. Over the years, several studies have reported a global decline in semen quality. While both genetic and environmental factors can cause such changes, most researchers attribute the sharp decline to air pollution. Now, researchers in China have found evidence of poor sperm motility in men exposed to high air pollution.
Particulate matter (PM) is considered the most harmful form of air pollution. They are generally composed of dust, carbon, nitrates, ammonia, sulfate, sodium chloride, and water. Some have a diameter of 10 micrometers (PM10) and others are superfine with a diameter of 2.5 μm or less. Chronic exposure to high concentrations of these small particulates can lead to respiratory and cardiovascular diseases. Moreover, prrevious studies have linked air pollution to irreversible vision loss, dementia, and cardiac changes in children.
Study Points at Need for Better Air Quality
The team of researchers analyzed the health records of more than 30,000 male patients at fertility clinics across China. They first separated the men into four groups based on the degree of air pollution in their area. Next, researchers looked at their sperm examination results which included sperm count, motility, and degree of concentration.
According to the results, researchers did not observe any link between air pollution levels and sperm count or concentration. However, they did note a significant reduction in sperm motility among those living in areas of high pollution. Men exposed to less than 2.5 micrometers of particulate matter had a 3.6% decrease in motility. While exposure to micrometers of particulate matter caused an average 2.44% drop in motility. Thus, providing evidence that exposure to particulate air pollution during sperm development can cause a decline in sperm motility.
Yan Zhao et al, Association of Exposure to Particulate Matter Air Pollution With Semen Quality Among Men in China, JAMA Network Open (2022). DOI: 10.1001/jamanetworkopen.2021.48684