POWER LINE WORKER EXPOSURE TO ELECTROMAGNETIC FIELDS: A SIMULATION STUDY

1. POWER LINE WORKER EXPOSURE TO ELECTROMAGNETIC FIELDS: A SIMULATION STUDY Dr. Nabil Maalej Physics Department 14-5-2006

2. Acknowledgement • Work is supported by KFUPM and the Saudi Electric Company through an RI Grant • Team Dr. Ibrahim Habiballah Dr. Chokri Belhaj Ahmed Dr. Nabil Maalej Pr. Mahmoud Dawoud Dr. Tarek Abdel-Galil Dr. Husain Masoudi Mr. Arif. Abdul-Majeed Mr. Khaled Al-Soufi

3. Outline • Effect of Extremely Low Frequency Electromagnetic Fields on Human Body(ELF) • IEEE Standard for Maximum Permissible Exposure • Calculation of External Electric and Magnetic Fields • Calculation of Internal Induced Current Densities and Electric Fields • Compliance with the Standards

4. Body in a Electric Field

5. Body in a Magnetic Field

6. Electric Effects • The induction of flow of electric charges (current) • The polarization of bound charges (formation of electric dipoles) • Reorientation of the electric dipoles already present in the tissues • Induced surface charge in the body which results in induced currents inside the body

7. Long Term Possible Effect of ELF • Some investigations have reported some correlation between childhood leukemia and exposures to high magnetic fields (McBride, 1999) (Green, 1999). • The results of various studies of childhood leukemia and adult cancer in occupational exposures are not consistent and are not conclusive (NRC, 1996) (NIEHS, 1998). • Most recent reviews of the long term effect of EM fields concluded that none of the long term hazard have been confirmed.

8. Short Term Effect of ELF • Aversive or painful stimulation of sensory or motor neurons • Muscle excitation that may lead to injury while performing potentially hazardous activities • Excitation of neurons or direct alteration of synaptic activity within the brain • Cardiac excitation • Adverse effects associated with induced potentials or forces on rapidly moving charges within the body, such as in blood flow.

9. Current Density and Short Term Effects of ELF The research literature has shown the following effects for the various current densities : • Between 1 and 10 mA/m2 , minor biological responses reported • Between 10 and 100 mA/m2 , visual and nervous system effects occur • Between 100 and 1000 mA/m2 , stimulation of excitable tissue is observed leading to possible adverse reactions • Above 1000 mA/m2 , extra systoles and ventricular fibrillation can occur (acute health hazards)

10. IEEE Standard For Safety levels • The IEEE Maximum exposure limits are based on avoidance of the short-term effects • Publication ( IEEE Std C95.6, “IEEE Standard for Safety Levels with Respect to Human Exposure to Electromagnetic Fields, 0–3 kHz”. 2002 ) :

11. External Exposure Limits

12. IEEE Basic Restriction for Induced Electric Fields

13. IEEE Basic Restriction for Induced Electric Fields at 60 Hz

14. Transmission Line Data

15. Exposure Scenarios Double circuit line: Nominal voltage 132 kV, Power ratings 293 MVA.

16. Exposure Scenarios

17. Exposure Scenarios

18. External Field Calculations • Calculation of External Electric Field • Methodology: Charge Simulation Method • Software: EMF Workstation • Provider: EPRI • Calculation of External Magnetic Field • Methodology: Biot Savart law • Software: EMF Workstation • Provider: EPRI

19. Calculation of External Electric Field Electric Field Profile (1 m above ground)

20. Calculation of External Electric Field Electric Field Profile (1 m above ground)

21. Calculation of External Magnetic Field Magnetic Field Profile (1 m above ground)

22. Calculation of External Magnetic Field Magnetic Field Profile (1 m above ground)

23. Summary of External Exposure Results for all Scenarios 4.95 kV/m 521 mG 4.95 kV/m 521 mG 6.06 kV/m 621 mG 6.48 kV/m 664 mG 0.77 kV/m 40.8 mG 0.165 kV/m 21.4 mG 1.69 kV/m 91.4 mG 1.8 kV/m 105 mG 0.745 kV/m 37.3 mG

24. External Electric Fields for all Exposure Scenarios

25. External Magnetic Fields for all Exposure Scenarios

26. Compliance with International Standards for Electric Fields

27. Compliance with International Standards for Magnetic Fields

28. Internal Induced Current Density and Electric Field Calculations • EMPIRE Software, IMST Germany • Theory: FDTD method • FDTD is a versatile method for numerical dosimetric calculation

29. Finite Difference Time Domain (FTDT) Method • A numerical technique to solve the Maxwell’s equation to study the electromagnetic fields interaction with materials. • The equations are expanded as a first order derivative, where the Finite–Difference technique is used to discretize the field components and their time and spatial derivatives. • The material is subdivided into cells with electrical properties properties represented by permittivity, permeability and conductivity • Time-iterative process is used to advance the excitation fields along the direction of propagation until convergence is reached.

30. FTDT Method D [C/m2] and B [T] are the electric and magnetic flux densities E [V/m] and H [A/m] are the electric and magnetic fields J [A/m2]is the current density Material properties: permittivity  , permeability  , conductivity 

31. Anatomical Body Model Data * AFRL: Air Force Research Laboratory (AFRL)

32. Tissue Conductivity at 60 Hz

33. Tissue Properties Variation with Frequency(Camelia Gabriel)

34. EMPIRE Output

35. MATLAB Output Post Processing • Layer average and maximum values • Mapping of numerical results with body tissues • Calculation of tissue average and maximum values • Localization of voxels of maximum values

36. Scenario 4 Results

37. Scenario 4: The layer Javg and Jmax

38. Scenario 4: The layer Eavg and Emax

39. Scenario 4: The location of maximum induced current density in the brain location of maximum induced current density Anatomical structure of brain

40. Scenario 4: The location of maximum induced current density in the heart

41. Compliance with the Basic Restrictions for Internal Values for Current Densities

42. Compliance with the Basic Restrictions for Internal Values of Electric Fields

43. Compliance with the Basic Restrictions for Internal Values of Electric Fields

44. Compliance with the Basic Restrictions for Internal Values of Electric Fields

45. Compliance with the Basic Restrictions for Internal Values of Electric Fields

46. Conclusion • For all worker scenarios around the 132 kV power transmission line the external maximum permissible exposures for E and B fields were not exceeded • The induced current densities and electric fields were all below the maximum permissible exposure limits • The worker is safe from short term adverse effects of 132 kV, 60 Hz High voltage transmissions line

47. Thank You

48. Summary of External Field Exposure “ Input to Empire”

49. Standards • IEEE Std C95.6, “IEEE Standard for Safety Levels with Respect to Human Exposure to Electromagnetic Fields, 0–3 kHz”. 2002. • International Commission on Non-Ionizing Radiation Protection (ICNIRP), “Guidelines limiting exposure to time-varying electric, magnetic, and electromagnetic fields (up to 300 GHz),”. • National Radiological Protection Board, UK (NRPB) “ELF Electromagnetic fields and the risk of cancer”. • Publication of American Conference of Governmental Industrial Hygienists (ACGIH) “Radio-Frequency and ELF Electromagnetic Energies: A Handbook for Health Professionals”  

50. High Frequency Limits Maximum permissible exposure (MPE) limits of American National Standards Institute (ANSI)/IEEE C95.1-1991. The valley at a frequency of 100 MHz approximately corresponds to resonance of the human body.