The air pollution has reached critical levels in Sarajevo as a result of the use of solid fuels for heating during the winter and thousands of old cars in the city streets that use fuels below the Euro III standards.
The Bosnian capital, situated in a depression, has been covered by thickening smog for two weeks, with no sufficient circulation of the air due to temperature inversions, with temperatures on hills overlooking the city being higher than air temperatures in the city itself.
On Wednesday, local air quality monitoring stations measured a concentration of 300 micrograms of dust per cubic metre, while the EU standard limit is 25 micrograms per cubic meter.
This prompted local authorities to issue warnings on Thursday, recommending locals to stay at home or wear masks outdoors.
All manufacturing plants using solid fuels were instructed to reduce their operational capacities or lower temperatures by three centigrades.
Apart from Sarajevo, also Zenica and Tuzla, two industrial hubs, have been coated in dense smog for days.