1: The world's most polluted countries face severe air quality issues.

2: China ranks high among the most polluted countries due to rapid industrialization.

3: India struggles with pollution from vehicle emissions and industrial waste.

4: Bangladesh faces pollution challenges from industrial growth and population density.

5: Pakistan deals with pollution from vehicles, industries, and agricultural practices.

6: Indonesia battles pollution from deforestation, agriculture, and urbanization.

7: Nigeria suffers from pollution caused by oil spills and industrial emissions.

8: Saudi Arabia's oil industry contributes to its pollution levels.

9: Iran faces pollution issues from industrial growth and vehicle emissions.