Overview

• A 21-year cohort of nearly four million Danish adults found that higher lifetime exposure to traffic-related pollutants is associated with increased risk of meningioma, the most common primary brain tumour.
• Each 5,747-particle/cm³ rise in ultrafine particles corresponded to a 10% increase in meningioma risk, with comparable exposure–risk increases observed for PM2.5, nitrogen dioxide and elemental carbon.
• Ultrafine particles were confirmed to cross the blood–brain barrier, suggesting a potential mechanism for how traffic pollution may impact brain tissue.
• The analysis did not detect significant associations between pollutant exposure and more aggressive gliomas, indicating a specific link to meningioma.
• Researchers emphasized that the findings demonstrate correlation rather than causation and urged further studies alongside tighter air quality measures to potentially reduce brain tumour incidence.