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MEASUREMENT OF ELECTRIC AND MAGNETIC FIELD STRENGTHS FROM INDUSTRIAL RADIOFREQUENCY (15-40.68 MHz) POWER SOURCES

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D. L. Conover, W. H. Parr, E. L. Sensintaffar, W. E. Murray Jr. · 1975

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Eighty percent of RF sources exceeded 1975 safety guidelines, revealing decades-old patterns of inadequate EMF monitoring and overexposure.

Plain English Summary

Summary written for general audiences

This 1975 NIOSH study tested radiofrequency field-strength monitors designed to measure worker exposures near RF power sources (15-40 MHz). The preliminary survey found that at least 80% of RF sources exceeded the safety guidelines for both electric and magnetic fields specified in the 1974 ANSI standard. The research highlighted critical gaps in proper RF exposure monitoring techniques for worker protection.

Why This Matters

This pioneering occupational health study reveals a troubling pattern that continues today: widespread RF exposures exceeding safety standards, combined with inadequate monitoring practices. The finding that 80% of RF sources exceeded guidelines in 1975 demonstrates that EMF overexposure has been a persistent industrial problem for decades. What makes this particularly relevant is the researchers' emphasis on near-field measurements, which capture the magnetic field component often ignored by standard power density meters. This same measurement gap exists today with modern wireless devices. The study's call for proper federal monitoring standards was prescient, as we still struggle with inconsistent EMF measurement protocols across industries. The reality is that without proper field-strength monitoring, we cannot accurately assess exposure risks for workers or consumers.

Exposure Information

Specific exposure levels were not quantified in this study.

Cite This Study
D. L. Conover, W. H. Parr, E. L. Sensintaffar, W. E. Murray Jr. (1975). MEASUREMENT OF ELECTRIC AND MAGNETIC FIELD STRENGTHS FROM INDUSTRIAL RADIOFREQUENCY (15-40.68 MHz) POWER SOURCES.
Show BibTeX
@article{measurement_of_electric_and_magnetic_field_strengths_from_industrial_radiofreque_g4915,
  author = {D. L. Conover and W. H. Parr and E. L. Sensintaffar and W. E. Murray Jr.},
  title = {MEASUREMENT OF ELECTRIC AND MAGNETIC FIELD STRENGTHS FROM INDUSTRIAL RADIOFREQUENCY (15-40.68 MHz) POWER SOURCES},
  year = {1975},
  
  
}

Quick Questions About This Study

At least 80% of radiofrequency sources tested exceeded the electric and magnetic field strength guidelines (200 V/m and 0.5 A/m respectively) specified in the 1974 ANSI Personnel Exposure Standard for RF radiation.
Near-field measurements were essential because personnel operating RF power sources receive exposures within fractions of a wavelength from the source, where magnetic field effects predominate and standard far-field power density monitors provide inaccurate readings.
The NIOSH study focused on radiofrequency sources operating between 15 to 40.68 MHz, which required specialized near-field monitoring equipment rather than standard commercial far-field power density monitors with dipole antenna elements.
Researchers found widespread use of totally incorrect RF exposure monitoring techniques and instrumentation, partially due to the absence of federal personnel exposure standards specifying proper field-strength measurements for RF sources between 10-300 MHz.
Under near-field conditions, magnetic field-induced power absorption predominated over electric field effects, making standard commercial power density monitors inadequate for accurate worker exposure assessment near RF sources operating at these frequencies.