Determination of the long-term impact of air particulates and air pollution mix on health. This involves identification of the critical component and size of particulate pollution; identification and quantification of the most important pollution source(s); identification of mechanisms of effects related to short-term and long-term exposure to particles and air pollution mix, considering their physical and chemical characterization and source apportionment; and improving understanding of the effects of long-term exposure to particulate matter and air pollution mix.
However, there are considerable uncertainties about the magnitude of their impact on human health, especially their contribution to the risk of chronic disease and mortality in comparison to that of other non-particle pollutants. Further information is required about the characteristics of the particles or air pollution mix that present the most serious risk.