The Environmental Health Criteria Programme (EHC) evaluates information on the relationship between exposure to environmental pollutants and human health, in order to establish guidelines for setting exposure limits. This publication focuses on the risks posed by exposures to selected nitro-and nitro-oxy-polycyclic aromatic hydrocarbons (nitroPAHs). These are derivaties of polycyclic aromatic hydrocarbons (PAHS) which contain two or more fused aromatic rings made of carbon and hydrogen atoms.