Sarajevo, the capital of Bosnia and Herzegovina, ranked as the world’s most polluted city today, with an air quality index of 485—63 times above WHO safety standards, according to IQAir. Residents were advised to avoid outdoor exercise, keep windows closed, and wear masks due to health risks.

The Sarajevo Canton Government activated the “alert” level of its Emergency Measures Plan. Experts attribute the pollution to winter temperature inversions, low-quality heating fuels, aging diesel vehicles, and the city’s geography, which traps pollutants. Improved weather conditions are expected within days.