Overview

• The systematic review and meta-analysis of 51 studies covering over 29 million participants found that each 10 µg/m³ increase in PM2.5 is linked to a 17% rise in dementia risk.
• Exposure to nitrogen dioxide raised dementia risk by 3% per 10 µg/m³, while each 1 µg/m³ increase in soot corresponded to a 13% higher risk.
• Researchers highlight inflammation in the brain and oxidative stress as the main biological pathways by which pollutants may trigger cognitive decline.
• Most included studies involved white participants in high-income countries, underscoring the need for more diverse research and data from marginalized populations.
• Authors urge stricter pollutant limits and equity-focused air quality policies at regional, national and international levels to protect communities facing higher exposure.