Currently, Valjevo and Niš are the cities with the most polluted air in Serbia. According to the Environmental Protection Agency, in the past 24 hours, the average value of suspended particles and heavy metals (lead, arsenic, cadmium and nickel) was 184 milligrams per cubic meter in Valjevo and 154 micrograms in Nis.
In order to say that the air is clean, the average value of suspended particles and heavy metals should not exceed 50 micrograms per meter cubic meter. Elevated values of this parameter were measured in Belgrade (80 micrograms), Novi Sad (71), Subotica (76), Smederevo (94) and Bor (59).
Source: http://rs.n1info.com/Zdravlje/a440829/Nis-i-Valjevo-gradovi-sa-najzagadjenijim-vazduhom.html
