Bosnia's capital Sarajevo has been enveloped in smog for days.
Forecasters say the higher-than-normal amount of pollution will clear in the coming days, but the risk to residents' health is expected to continue into winter.
The number of particles produced by car exhausts can be so high it causes the measuring equipment to break down.
Al Jazeera's Ivan Pavkovic reports from Sarajevo.
Source: Al Jazeera