A study known as the XENAIR study, conducted by the Centre Léon Bérard in Lyon, has found a possible link between exposure to multiple air pollutants and a higher risk of breast cancer. Researchers report that women most exposed to these pollutants have a risk up to 60% higher than those with the lowest exposure. The study, led by Professor Béatrice Fervers, director of the cancer prevention and environment department at the Centre Léon Bérard, has been ongoing since 2016. It is based on data from more than 10,000 women, including over 5,000 who were diagnosed with breast cancer between 1990 and 2011 and over 5,000 who were not. The latest findings, shared by the ARC Foundation, which funds the research, highlight that simultaneous exposure to several pollutants may increase the risk of breast cancer. The study previously identified five key pollutants: nitrogen dioxide (NO₂), fine particles PM10 and PM2.5, benzo(a)pyrene, and PCB153. More recent analyses have focused on the combined effects of these pollutants. According to Fervers, the increased risk was observed among women living in densely populated urban areas such as Lyon and Paris, where exposure to high levels of NO₂, PCB, and PM is more common. Researchers emphasize that while the findings suggest a correlation between pollution and breast cancer risk, they do not prove that pollution is the sole cause of the disease. Professor Fervers notes that reducing the concentration of these four pollutants in the air could help lower the risk of breast cancer. Her team is now exploring the role of other pollutants, including PFAS, which are a group of synthetic chemicals used in various industrial and consumer products. The researchers also aim to create a platform that can reconstruct individual environmental exposures over several decades. This would help better understand how long-term exposure to pollutants may influence health outcomes. The study continues to shed light on the complex relationship between air quality and cancer risk, offering insights that could inform public health policies and environmental regulations.