Researchers from the Danish Institute for Cancer Research as part of a research team have found that air pollution and traffic noise are directly linked to an increased risk of infertility in both men and women. The results of the study were published on PubMed. Scientists studied information about people of reproductive age, potentially capable of becoming parents for the first or next time. From them, 900 thousand Danes aged 30-45 years, who lived with a partner or were married, were selected to participate in the study. After excluding some participants for health and lifestyle reasons, the final study list included 377,800 women and 526,000 men. Over the course of five years, the researchers analyzed the extent to which participants were exposed to traffic noise (measured in decibels) and fine particulate matter air pollution (PM2.5). The results showed that men were 24% more likely to be infertile when the concentration of such particulate matter in the air increased. Women over the age of 35 were also found to be at risk - noise levels 10 decibels higher than normal increased the likelihood of fertility problems by about 14%. The authors of the study explained that the male reproductive system is more vulnerable to rapid changes in the environment, because sperm are constantly renewed. Female eggs, on the contrary, are formed before birth and have better protection from negative factors, although with age, such protection may weaken. The scientists also noted that despite the significance of the findings, the study has limitations. The scientific work did not take into account biological parameters such as hormonal changes or body mass index, as well as the amount of time people spend outdoors, where the influence of pollutants can also negatively affect health.