Most polluted state in World : The last 2025/2026 World Air Quality Report (last updated late March 2026) suggests the pollution index measured by $PM_{2.5}$ (fine particulate matter).
The term “state”, however, includes countries or the provinces within some larger regional states — and South Asia is currently the most affected region in the world.
Most Polluted Countries Data (2025/26)
Such indices are derived from the population-weighted annual average of $PM_{2.5}$ ($\mu g/m^3$) observable until October 2023 in these countries. For the sake of comparison, the WHO safety guideline is only 5 $\mu g/m^3$.
According to the latest (late March 2026) 2025/2026 World Air Quality Report, pollution is mainly reported and measured in regards to the concentration of PM2. 5 (fine particulate matter).
While “state” may mean a country or state, at present South Asia is the most affected region in the world.
Most Polluted Countries (data from 2025/26)
These rankings are determined by the annual average of PM2. 5 (μg/m3). In comparison, the WHO safety guideline is only 5 μg/m3.
| Rank | Country | Avg. PM2.5 (μg/m3) | Key Contributing Factors |
| 1 | Pakistan | 67.3 | Industrial smog, vehicular emissions |
| 2 | Bangladesh | 66.1 | Construction dust, brick kilns |
| 3 | Tajikistan | 57.3 | Fossil fuel heating, regional dust |
| 4 | Chad | 53.6 | Saharan dust storms |
| 5 | DR Congo | 50.2 | Biomass burning, lack of monitoring |
| 6 | India | 48.9 | Crop burning, coal power plants |
| 7 | Egypt | 47.1 | Urban congestion, desert dust |
| 8 | Iraq | 45.8 | Oil industry flares, dust storms |
| 9 | Kuwait | 44.2 | Sandstorms, petroleum activity |
| 10 | Bahrain | 43.5 | Rapid urbanization, limited greenery |
Most Polluted Regions/Cities
If you are searching for particular “states” (provinces or territories), the Indo-Gangetic Plain continues to be the world’s most toxic corridor. A few cities in Uttar Pradesh (India) and the Punjab (Pakistan) invariably dominate.
1 Loni, Uttar Pradesh (India) 148.2 11.7 Loni retained its position as the most polluted city in the world as per latest report with an average PM2. 5 of 112.5 μg/m3.
Hotan, Xinjiang (China): #2 in the world — industrial activity and natural dust.
New Delhi (India): For the eighth year in a row, retains title as world’s most polluted capital city.
Lahore (Pakistan): Often trades with Delhi and Loni for the worst daily AQI readings.
Why the Rankings Shift
Note: Interestingly, Chad was #1 in 2024 and dropped to #4 in 2026 This may not, however, be due to an actual reduction in air quality but rather “monitoring gaps,” experts say, with many tracking stations recently being closed down across Africa.
