Across Central Asia, rapid urban growth, magnified by the region’s pollution-trapping geography and meteorological conditions, has pushed several capitals and major cities into the ranks of the world’s most polluted.

Bishkek in Kyrgyzstan, Almaty in Kazakhstan, and Tashkent in Uzbekistan have repeatedly ranked among the global top 10 for air pollution since the start of January, while some cities in the region experience hazardous air levels for months out of the year. 

Here’s what is driving the crisis.