According to Swiss-based air quality monitoring organization IQAir, India dominates the list of the world’s most polluted cities, with Delhi, Kolkata, and Mumbai among the top five. Delhi tops the list with an Air Quality Index (AQI) score of 450, indicating hazardous air conditions. Kolkata follows with a score of 248, while Dhaka, the capital of Bangladesh, ranks third with a score of 232, categorized as very unhealthy. Pakistan’s Karachi is fourth with 209, and Mumbai is fifth with 198. IQAir’s scale classifies air quality between 0–50 as good, 51–100 as moderate, 101–150 as unhealthy for sensitive groups, 151–200 as unhealthy, 201–300 as very unhealthy, and above 301 as hazardous. The data, collected on Sunday morning, highlights the severe air pollution crisis affecting major South Asian cities, posing serious health risks to millions of residents.