Human perception of electric fields and ion currents associated with high-voltage DC transmission lines

Abstract

The objective of this study was to assess the ability of humans to detect the presence of DC electric fields and ion currents. An exposure chamber simulating conditions present in the vicinity of high‐voltage DC (HVDC) lines was designed and built for this purpose. In these experiments, the facility was used to expose observers to DC electric fields up to 50 kV/m and ion current densities up to 120 nA/m2. Forty‐eight volunteers (25 women and 23 men) between the ages of 18 and 57 years served as observers. Perception of DC fields was examined by using two psychophysical methods: an adaptive staircase procedure and a rating method derived from signal‐detection theory. Subjects completed three different series of observations by using each of these methods: one was conducted without ion currents, and the other two involved various combinations of electric fields and ion currents. Overall, subjects were significantly more likely to detect DC fields as the intensity increased. Observers were able to detect the presence of DC fields alone, but only at high intensities; the average threshold was 45 kV/m. Except in the most sensitive individuals, ion current densities up to 60 nA/m2 did not significantly facilitate the detection of DC fields. However, higher ion current densities were associated with a substantial lowering of sensory thresholds in a large majority of observers. Data analysis also revealed large variations in perceptual thresholds among observers. Normative data indicating DC field and ion current intensities that can be detected by 50% of all observers are provided. In addition, for the most sensitive observers, several other detection proportions were derived from the distribution of individual detection capabilities. These data can form the basis for environmental guidelines relating to the design of HVDC lines. © 1996 Wiley‐Liss, Inc.

Biological effects of exposure to static electric fields in humans and vertebrates: a systematic review

“…Field perception experiments provided evidence that detection thresholds for static EF are much lower for whole-body exposure [29, 31] than limb exposure (e.g., arm and forehand) [30, 34]. Because these effects were confirmed by independent investigators, they can be considered as replicated.…”

“…Because these effects were confirmed by independent investigators, they can be considered as replicated. Blondin et al [29] found that under whole-body exposure (static EF strength up to 50 kV/m, 7–11 s/trial) the median detection threshold of seated and grounded male and female subjects was 45.1 kV/m for a static EF. Approximately, 5% of the participants could detect a static EF below 20 kV/m, 33% of the subjects detected a static EF below 40 kV/m and 66% detected fields below 50 kV/m.…”

“…Such a field increase in the head/shoulder region should facilitate the perception of the field. The notable field increases may also explain why both Blondin et al [29] and Clairmont et al [31] reported that some people are able to detect static EF at field strengths of 10 kV/m and even below that level. Field perturbation occurs much less when only the forearm is exposed because of the comparatively flat shape of the arm.…”

“…or combined with air ions?) for approximately 1 hphysiological/health-related effects:blood parameters; respiration rate; pulse; blood pressure; brightness detection; reaction times; field awareness; muscular steadinessno significant effectalso air ions tested; not clear if peer-reviewed, all subjects were pilotsBlondin et al [29]whole-body( n  = 48)static EF of <10 to 50 kV/m alone or in combination with air ions; 7–11 s per trial (several 100 trials during 1 day)field perceptionmedian perception threshold 45.1 kV/m without ions; high ion densities lowered the median threshold to 36.9 kV/mChapman et al [30]arm( n  = 16)static EF of 30 to 65 kV/m; 7–11 s per trial (several 80 trials during 1 day)field perceptionsubjects did not perceive static EFalso AC EFClairmont et al [31]whole-bodystatic EF of −40 to 40 kV/m alone or combined with different AC EFfield perceptionperception threshold of static EF 10–20 kV/m; simultaneous AC EF lowered the thresholdmain focus was technicalHaupt and Nolfi [35]whole-body( n  = 438)static EF of approx. −16 to 21 kV/m and static MF of 22 μT of a HVDC line for at least 5 yearsphysiological/health-related effects:self-reported health issues (e.g., headache, depression, allergies, illness days)no significant effectcross-sectional epidemiological studyOdagiri-Shimizu and Shimizu [34]human arm ( n  = 10–30 per condition)static EF up to 450 kV/m with variable humidityfield perceptionaverage perception threshold approx.…”

DC ion-currents in AC conductors in hybrid AC/DC transmission systems

“…At ground level ion currents can lead to charging of objects and thus to undesirable spark discharges and human annoyance [5,6,7]. DC ion currents in AC phases lead to a stronger magnetization of transformers, which manifests itself in higher losses and noise emission [8].…”