Related Experiment Video
Updated: Jul 12, 2026
09:30
Quantitative Magnetic Resonance Imaging of Skeletal Muscle Disease
Published on: December 18, 2016
Magnetic fields from steel-belted radial tires: implications for epidemiologic studies
S Milham1, J B Hatfield, R Tell
1Gravelly Beach Loop NW, Olympia, Washington. smilham@halcyon.com
Bioelectromagnetics
|September 24, 1999
Summary
Radial tires generate extremely low frequency (ELF) magnetic fields from steel wire belts. These fields, often below 20 Hz, may be missed in health studies, potentially affecting exposure assessments.
Area of Science:
- Electromagnetism
- Environmental Health
- Vehicle Engineering
Background:
- Radial tires contain magnetized steel wire belts.
- Tire rotation generates alternating extremely low frequency (ELF) magnetic fields, typically under 20 Hz.
- These fields possess a fundamental frequency tied to rotation rate and exhibit high harmonic content.
Purpose of the Study:
- To characterize the static and alternating magnetic fields generated by radial tires.
- To assess the impact of degaussing on these tire-generated magnetic fields.
- To highlight potential issues for exposure assessments in health studies due to undetected ELF fields.
Main Methods:
- Measurement of static and alternating magnetic fields at the tire tread and within the vehicle passenger compartment.
- Evaluation of magnetic field levels before and after tire degaussing.
- Analysis of the frequency characteristics of the generated fields.
Main Results:
- Static magnetic fields at the tread can exceed 500 microT.
- Alternating fields in the passenger compartment can exceed 2.0 microT.
- Degaussing effectively reduces both static and alternating fields, but they gradually increase over time.
Conclusions:
- Radial tires are a source of ELF magnetic fields.
- The frequencies of these fields may fall below the detection limits of standard magnetic field meters used in health studies.
- Failure to account for these tire-generated fields could lead to compromised exposure assessments in epidemiological research.
Related Concept Videos
01:16Magnetic Field Of A Current Loop
Consider a circular loop with a radius a, that carries a current I. The magnetic field due to the current at an arbitrary point P along the axis of the loop can be calculated using the Biot-Savart law.
01:25Eddy Currents
Since eddy currents occur only in conductors, magnets can separate metals from other materials. For example, in a recycling center, trash is dumped in batches down a ramp, beneath which lies a powerful magnet. Conductors in the trash are slowed by eddy currents, while nonmetals in the trash move on, separating from the metals. This works for all metals, not just ferromagnetic ones.
Other major applications of eddy currents appear in metal detectors and the braking systems of trains and roller...
Other major applications of eddy currents appear in metal detectors and the braking systems of trains and roller...
01:24Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) is a noninvasive medical imaging technique based on a phenomenon of nuclear physics discovered in the 1930s, in which matter exposed to magnetic fields and radio waves was found to emit radio signals. In 1970, a physician and researcher named Raymond Damadian noticed that malignant (cancerous) tissue gave off different signals than normal body tissue. He applied for a patent for the first MRI scanning device in clinical use by the early 1980s. The early MRI...
01:28Flat Belts: Problem Solving
Flat belts are crucial in many industrial applications as they help transmit power from one pulley to another. The concept of forces and moments is used to determine the maximum moment on a pulley. For instance, consider a flat belt that wraps around two pulleys, A and B, with radii of 30 cm and 10 cm, respectively. The angle between the belt and the horizontal is 20 degrees at the pulleys. As pulley B rotates clockwise and drives pulley A, tension T2 is caused at one end of the belt, while...
01:21Rolling Resistance
When a solid cylinder rolls steadily on a rigid surface, the normal force applied by the surface on the cylinder is perpendicular to the tangent at the contact point. However, since no materials are entirely rigid, the surface's reaction to the cylinder involves a range of normal pressures.
For instance, imagine a hard cylinder rolling on a comparatively soft surface. The cylinder's weight compresses the surface beneath it. As the cylinder moves, the material in front of it slows down due to...
For instance, imagine a hard cylinder rolling on a comparatively soft surface. The cylinder's weight compresses the surface beneath it. As the cylinder moves, the material in front of it slows down due to...
01:18Other Unique Bacteria
Magnetic bacteria exhibit a directed movement called magnetotaxis, driven by structures called magnetosomes. These magnetosomes consist of chains of magnetic particles made of either magnetite (Fe₃O₄) or greigite (Fe₃S₄) and are organized in a linear conformation by a protein scaffold within invaginations of the cell membrane. The bacteria align along the north–south magnetic field lines, much like a compass needle. They are typically microaerophilic or anaerobic and are commonly found near the...