The chemical composition of particulate matter can be very diverse, comprising a range of toxic compounds. Exposure to airborne particulate matter has been considered a substantial health risk for two decades now. There is no scientific evidence for a safe exposure limit. Therefore, current exposure levels across Europe are reason for concern. Exposure to particulate matter in adults may cause severe respiratory and cardiovascular disease. There is abundant epidemiological evidence that children, and younger children in particular, are more susceptible to the adverse effects of particular matter on health than adults. Short term exposure of children may already cause respiratory symptoms and allergic reactions. Environmental health policies reducing risks of exposure to particulate matter in children are recommended.