Hedley Environmental Index (HEI) is calculated based on five criteria pollutants with reference to World Health Organization Air Quality Guideline. The HEI is the real-time median of all urban rooftop stations.
For more details, please refer to FAQ.
27 Jul 2021, 00:00:00
| Band | HEI | Station |
| low | 1-3 | |
| moderate | 4-6 | |
| high | 7-9 |
|
| very high | 10-12 |
|
| serious | 12+ |
|
| not available | NA |
|