| AQI | Air Quality Index |
| PM10 | Particles with aerodynamic diameter ≤ 10 µm |
| PM2.5 | Particles with aerodynamic diameter ≤ 2.5 µm |
| NO2 | Nitrogen Dioxide |
| SO2 | Sulfur Dioxide |
| CO | Carbon Monoxide |
| AOD | Aerosol Optical Depth |
| IAQI | Individual Air Quality Index |
| IAQIp | Air quality sub-index for pollutant p |
| Cp | Concentration of pollutant p |
| CLo | Concentration breakpoint that is ≤C |
| CHi | Concentration breakpoint that is ≥C |
| IAQILo | Index breakpoint corresponding to CLo |
| IAQIHi | Index breakpoint corresponding to CHi |
| CAAQS | Chinese Ambient Air Quality Standards |
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