What is the top ten dirtiest cities in world?

According to the World Health Organization (WHO), the top 10 most polluted cities in the world in 2016 (by PM2.5 concentration) are:

1. Zabol, Iran (217 µg/m³)

2. Gwalior, India (176 µg/m³)

3. Allahabad, India (170 µg/m³)

4. Raipur, India (169 µg/m³)

5. Kanpur, India (168 µg/m³)

6. Varanasi, India (159 µg/m³)

7. Delhi, India (143 µg/m³)

8. Patna, India (142 µg/m³)

9. Lucknow, India (141 µg/m³)

10. Agra, India (138 µg/m³)

It's important to note that these rankings are based on data from 2016, and there may have been changes since then. Additionally, pollution levels can vary significantly within a city, depending on factors such as traffic congestion, industrial activity, and weather conditions.