Table 1.
Summary statistics of CH, gaseous air pollutants, temperature, and toxic metal in wastewater in 30 provinces of China
| Indicatorsa | Mean | SD | P25 | P50 | P75 |
|---|---|---|---|---|---|
| CH | 4.049 | 1.570 | 2.818 | 3.615 | 5.038 |
| SO2 | 31.329 | 14.481 | 21.292 | 28.818 | 42.096 |
| NO2 | 35.264 | 8.420 | 29.260 | 35.225 | 39.041 |
| CO | 1.176 | 0.291 | 0.988 | 1.174 | 1.325 |
| O3 | 80.462 | 13.127 | 69.729 | 81.931 | 90.367 |
| T | 29.307 | 5.800 | 10.240 | 16.058 | 18.304 |
| Pb | - | - | 129.150 | 784.650 | 3890.950 |
| Hg | - | - | 5.025 | 10.550 | 30.575 |
| As | - | - | 70.825 | 872.800 | 3387.625 |
| Cd | - | - | 12.600 | 171.150 | 794.250 |
SD standard difference, T temperature, P25 25th percentile of the toxic metal according to distribution, P50 50th percentile of the toxic metal according to distribution, P75 75th percentile of the toxic metal according to distribution
aThe unit of measurement for each indicator: 1 per 10,000 live birth for CH; μg/m3 for SO2, NO2, and O3; mg/m3 for CO; million tons for toxic metal in wastewater