Bosnian schoolchildren with face masks
© AP Photo/Amel EmricA group of school children walk on street with face mask in Sarajevo, Bosnia, on Wednesday, Dec. 23, 2015
Sarajevo authorities say they are closing down schools because of high pollution mixed with fog, and volunteers have begun distributing face masks to those who still decided to get out of the house despite warnings to reduce movement.

Schools are closing down after more than a month of dense fog, broken only by three or four clear days. Authorities said Wednesday it has been the longest siege of foul weather in decades.

Air pollution in Bosnia
© AP Photo/Amel EmricBosnian man walks on the street during fog in Sarajevo, Bosnia, on Tuesday, Dec. 22, 2015. Local authorities in Sarajevo advised the population to reduce movement in the mornings and evenings due to health risks caused by air pollution
Flights have been canceled for the past few days because of fog, a common occurrence at Sarajevo's airport in winter.

Meanwhile, people on social networks have been sharing photos of flocks of birds walking down streets, unable to fly because of reduced visibility.

Source: Associated Press