Does traffic-related air pollution increase risk of dementia?

Higher exposure to a certain type of traffic-related air pollution called particulate matter may be linked to an increased risk of dementia, according to a meta-analysis. Researchers specifically looked at fine particulate matter, PM2.5, which consists of pollutant particles of less than 2.5 microns in diameter suspended in air. The meta-analysis included all available studies on air pollution and risk of dementia.