Fine Structure of MF Variations (0-10 Hz) Onboard DC Electrified Trains

Biological experiments showed that, differently from ionizing radiation and most chemical factors, the effect of low-frequency magnetic fields (MF) appears to be highly non-linear, as indicated by the possible concern of intensity and frequency "windows", resonance-like phenomena, intermittence, transients and MF polarization. We present results of a magnetic survey performed during 1997-98 in Russia onboard DC trains. Studying the fine structure of transport-associated MF, we emphasize the importance of MF exposure parameters other than the customary considered time-weighted average field strength. Specifically, we consider the complex-frequency characteristics of these fields, including pulses, intermittent components, polarization and the sources of these potentially hazardous MF features. To measure magnetic fields we used a wave-form capture system (torsion-type magnetometer) developed by SPbFIZMIRAN (Russia). This computer-based device, with sampling rate up to 200 Hz, allows to capture a field profile and to characterize field amplitudes over time and frequency.