Southeast Asia’s Most Polluted Cities in 2025 – Where Is Air Quality the Worst?

Air pollution remains a major challenge in Southeast Asia, affecting public health and overall quality of life. Factors such as vehicle emissions, industrial activities, and land burning continue to worsen air quality across the region.

The latest report from IQAir, a Swiss-based technology company that monitors global air quality, reveals the most polluted cities in Southeast Asia as of January 31, 2025. Using the Air Quality Index (AQI), the report assesses pollution levels on a scale from 0 to 500—the higher the value, the worse the air quality in a city.

According to this data, air quality in several Southeast Asian cities has reached levels that pose significant health risks. The U.S. AQI system categorizes pollution levels using a color-coded scale, ranging from green (good) to brown (hazardous), to indicate associated health risks.

Here are the six AQI categories and their corresponding risk levels:

• Green (0-50): Good
• Yellow (51-100): Moderate
• Orange (101-150): Unhealthy for sensitive groups
• Red (151-200): Unhealthy
• Purple (201-300): Very unhealthy, serious health effects
• Brown (301-500): Hazardous, severe health risks for all

Below are the 10 most polluted cities in Southeast Asia, based on IQAir data as of January 31, 2025: