10 Most Polluted Regions in Indonesia Tonight (31/7)

Air quality in West Kalimantan tonight is the worst in Indonesia. Based on the Air Pollution Standard Index (ISPU) page of the Ministry of Environment and Forestry (KLHK) on Thursday (July 31, 2025) at 6:00 PM WIB, it was revealed that the air quality index in West Kalimantan was 130.

According to the Directorate of Air Pollution Control of KLHK, ISPU is a unitless number used to describe ambient air quality conditions at a certain location and is based on its impact on human health, aesthetic value, and other living things.

ISPU calculation is based on the measurement results of seven air pollutant parameters, namely PM10, PM2.5, NO2, SO2, CO, O3, and HC. Air pollutant parameter measurements are spread across 72 stations in various regions.

(Read: 10 Provinces Most Affected by Floods in 2024)

Based on Ministry of Environment and Forestry Regulation No. 14 of 2020 concerning the Air Pollution Standard Index, an ISPU in the range of 0-50 indicates good air quality, 51-100 means moderate air quality, and 101-200 indicates unhealthy air quality that is detrimental to humans, animals, and plants.

Next, very unhealthy air quality in the range of 201-300 can increase health risks for sensitive groups. Meanwhile, hazardous air quality in the range of more than 300 can seriously harm health and requires prompt handling.

Below West Kalimantan, North Sumatra ranks second worst in Indonesia with an air quality index of 99. Then, in third place is West Sumatra with an air quality index of 97.

This means that no region has hazardous air quality.

Here is the list of the 10 provinces with the worst air quality index in Indonesia on Thursday, July 31, 2025, at 6:00 PM WIB.

1. West Kalimantan: 130

2. North Sumatra: 99

3. West Sumatra: 97

4. Banten: 92

5. South Sumatra: 91

6. Riau: 89

7. North Sumatra: 88

8. DKI Jakarta: 78

9. West Java: 74

10. East Java: 71

(Read: 10 Provinces Most Affected by Floods in 2024)