Do urban inhabitants suffer an increased risk of diseases related to air pollution ?

In general, air pollution levels observed in cities are higher than those on the countryside. The pollutant having the largest long term impact on health is PM2.5. This is particulate matter with a diameter smaller than 2.5 µm. In Belgium, the chronical or long term exposure to PM2.5 results in an average decrease in life span of 7 to 9 months. In the larger agglomerations (such as Brussels) the PM2.5 concentrations are above average, thus the decrease in life span will also be (a couple of months) greater there.