The system of automatic state ambient air monitoring stations in Lithuania consists of 14 urban air quality monitoring stations operating in Vilnius, Kaunas, Klaipėda, Šiauliai, Panevėžys, Jonava, Kėdainiai, Naujoji Akmenė and Mažeikiai and 3 integrated monitoring stations operating in Aukštaitija, Žemaitija and Dzūkija National Parks. Concentrations of the following pollutants are measured at automatic air quality monitoring stations: particulate matter PM10, fine particulate matter PM2.5, nitrogen oxides (NO2, NOx, NO), sulfur dioxide (SO2), carbon monoxide (CO), ozone (O3), benzene, mercury. The tests and measurements shall be carried out in accordance with the requirements of Directives 2004/107/EC of the European Parliament and of the Council relating to arsenic, cadmium, mercury, nickel and polycyclic aromatic hydrocarbons in ambient air and 2008/50/EC on ambient air quality and cleaner air for Europe.