Increased copper emissions are associated with growth in road transport, while those of selenium and zinc are related to glass production. Estimated emissions of polychlorinated biphenyls (PCBs) (mainly due to incineration of industrial waste) increased, as did emissions of polycyclic aromatic hydrocarbons (PAHs) from combustion in manufacturing industry, representing more than 50% of total estimated emissions. There was also a slight decrease in the number of stations with exceedance of the N02 annual mean limit value: four stations in 2007 (two in Lisbon, one in Porto and one in Funchal) and three stations in 2008 (one in Lisbon, one in Porto and one in Braga).