Table 1. Power frequency electric field measurements (V/m).
School | N | M±IR | Min | P25 | P50 | P75 | Max | Reference limit# |
School A | 30 | 0.417±0.84 | 0.016 | 0.108 | 0.417 | 0.949 | 2.919 | 4000 V/m |
School B | 21 | 1.34±2.83** | 0.522 | 0.627 | 1.340 | 3.46 | 3.930 | 4000 V/m |
Reference limit came from the Technical Regulations on Environmental Impact Assessment of Electromagnetic Radiation Produced by 500 kV Ultrahigh Voltage Transmission and Transfer Power Engineering (HJ/T24-1998) in China.
Two-Independent Samples Nonparametric Test, Z = 3.981, p<0.001.
N = number of spot measurements; M = median = P50; IR = interquartile range = P75–P25.