Understanding the difference between therapeutic light, electrical emissions, and actual biological risk.
There's something peculiar happening in the red light therapy industry. Companies promote the biological benefits of electromagnetic radiation while advertising their products as having little or no electromagnetic field exposure. Reviewers hold EMF meters against red light panels, display numbers on a screen, and suggest those readings tell consumers something important about their health. Meanwhile, consumers are left trying to reconcile what they've been told about the dangers of electromagnetic fields with the therapeutic benefits being attributed to electromagnetic energy.
I've spent decades working with athletes, studying recovery technologies, and examining how physical and environmental exposures influence human physiology. I began incorporating infrared light and vibration into my work with professional athletes long before red light therapy panels became common consumer products. That experience has given me an appreciation for what these technologies may offer, along with a healthy skepticism about the way they're marketed.
When I see someone demonstrating an EMF meter against a red light panel, I'm interested in what the instrument is actually measuring. The frequency, the type of field, the distance from the device, and the duration of exposure all influence whether a reading has any biological significance. A number on a screen tells us very little until those details are established.
Understanding the Electromagnetic Spectrum
Electromagnetic radiation exists across an enormous range of frequencies and wavelengths. At one end are extremely low-frequency fields associated with electrical power systems. Moving upward in frequency, we encounter radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays. [1]
A magnetic field oscillating at 60 cycles per second behaves differently from a radiofrequency field operating at billions of cycles per second. Red light at 660 nanometers oscillates at approximately 454 trillion cycles per second, while near-infrared light at 850 nanometers operates at approximately 353 trillion cycles per second. These are wavelengths commonly found in red light therapy panels, and they occupy a very different part of the electromagnetic spectrum from the electrical fields detected by most consumer EMF meters.
The frequency of electromagnetic radiation influences the ways it can interact with biological tissue, although frequency alone cannot establish the potential for benefit or harm. Intensity, duration, the amount of energy absorbed, and the characteristics of the exposed tissue all contribute to the biological response.
Ionizing radiation carries sufficient energy per photon to remove electrons from atoms or molecules, which helps explain why X-rays and gamma rays can damage biological structures, including DNA. Red and near-infrared light are non-ionizing, with photon energies insufficient to produce that kind of direct ionization.
Non-ionizing radiation can still cause biological injury. Microwave radiation can heat tissue, intense visible light can damage the retina, excessive infrared exposure can produce thermal injury, and sufficiently strong low-frequency magnetic fields can induce electrical currents within the body. [2] The mechanisms differ, and understanding them is essential when interpreting exposure measurements.
What an EMF Meter Can Tell Us
A red light therapy panel contains several sources of electromagnetic energy. The LEDs produce the intended optical radiation, while the power supply, electronic drivers, and internal wiring generate incidental electric and magnetic fields associated with their operation.
Consumer EMF meters typically measure selected ranges of low-frequency electric fields, magnetic fields, or radiofrequency emissions. Their capabilities vary considerably, and many are unable to characterize the optical radiation produced by the LEDs. Even within their advertised measurement ranges, instruments differ in accuracy, frequency response, sensitivity, and how they process complex electrical signals.
During a typical product review, the meter is placed directly against the panel and then moved farther away. The reading falls with distance, and the reviewer may interpret the lower value as evidence of improved safety. The demonstration can be useful for comparing electrical emissions under similar conditions, but the biological interpretation requires more information.
For example, low-frequency magnetic fields are commonly reported in milligauss or microtesla. Twenty milligauss equals two microtesla. The International Commission on Non-Ionizing Radiation Protection established a general-public reference level of 200 microtesla for a 60-hertz magnetic field in its 2010 guidelines. [3]
That reference level addresses established adverse effects associated with low-frequency exposure, particularly effects involving induced electric fields and stimulation of excitable tissue. Applying the guidelines to a real device requires attention to its actual frequency content, waveform, measurement conditions, and the location of the person using it.
There is also a broader scientific history behind concerns about extremely low-frequency magnetic fields. Epidemiological studies have reported an association between prolonged residential exposure and childhood leukemia, leading the International Agency for Research on Cancer to classify extremely low-frequency magnetic fields as possibly carcinogenic to humans. The World Health Organization has reviewed that evidence, including its limitations and the uncertainty surrounding causation. [4, 5]
These findings deserve serious consideration. They concern exposure circumstances that differ substantially from a brief session near a red light therapy panel, and the existing research does not establish that an isolated meter reading predicts an individual's health risk.
For consumers trying to compare products, meaningful electrical-emission testing would identify the type of field, the frequencies involved, the instrument used, and the readings at realistic treatment distances. A measurement taken against the housing of a device may be informative for engineering purposes, but it does not necessarily represent the exposure experienced during normal operation.
The Science Behind Therapeutic Light
The phrase "zero EMF" has become increasingly common in red light therapy marketing. In practice, manufacturers generally use it to describe low incidental electrical or magnetic emissions. The optical radiation produced by the LEDs is itself electromagnetic energy, so the phrase requires a clear explanation of what was measured and under what conditions.
I have no objection to manufacturers reducing unnecessary electrical emissions. Good engineering should be encouraged, particularly when companies provide transparent measurements and independent testing. But a panel's electrical-emission profile represents only one part of its overall performance and safety.
Photobiomodulation research examines how red and near-infrared light interact with biological systems. Investigators have studied effects involving mitochondrial activity, cellular signaling, inflammation, tissue repair, pain, and other physiological processes. [6]
Cytochrome c oxidase, an enzyme complex involved in mitochondrial respiration, has received considerable attention as a possible participant in these responses. Researchers have also examined nitric oxide signaling, reactive oxygen species, ion channels, and other pathways through which light exposure may influence cellular activity. [6, 7]
The mechanisms remain under investigation, and clinical outcomes vary with the condition being treated. There is evidence supporting photobiomodulation in particular medical applications, while many of the broader claims found in consumer marketing still require more rigorous clinical evaluation. [8]
Treatment parameters are central to interpreting that research. Wavelength determines important characteristics of light absorption and penetration, while irradiance, treatment duration, distance, and the energy reaching the target tissue influence the delivered dose. Studies have also described nonlinear dose-response relationships in which increasing exposure beyond an effective range can reduce or alter the biological response. [6]
This is particularly relevant to the way red light panels are advertised. Electrical wattage is frequently displayed as though it represents the amount of therapeutic light reaching the body. In reality, electrical power consumption, optical output, irradiance at a particular distance, and the dose delivered to tissue are different measurements. A meaningful comparison requires information about the light the device actually produces and the conditions under which that output was measured.
Optical safety deserves consideration as well. IEC 62471 provides a framework for evaluating photobiological hazards associated with lamps and lamp systems, while applicable electrical safety and electromagnetic compatibility requirements address other aspects of equipment design. [9]
A well-characterized red light therapy panel should therefore be evaluated through several complementary measurements. Optical output helps establish what treatment is being delivered. Appropriate safety testing addresses foreseeable hazards. Electrical-emission measurements provide information about incidental fields generated by the equipment. Together, these allow a much more useful assessment than a single number displayed on a handheld meter.
What PEMF Adds to the Discussion
Pulsed electromagnetic field therapy provides another perspective on the relationship between electromagnetic exposure and biological response. PEMF devices deliberately generate changing magnetic fields that can induce electric fields within biological tissue. Frequency, waveform, magnetic flux density, exposure duration, and the physical arrangement of the treatment system influence the resulting exposure.
Certain PEMF devices have received regulatory authorization for specific medical uses, including bone-growth stimulation. [10] Those authorizations apply to defined devices and indications, and the evidence supporting them cannot automatically be extended to the wider range of wellness and athletic recovery products marketed under the PEMF label.
Having worked with recovery technologies for many years, I find this comparison particularly interesting. We have an industry in which deliberately generated electromagnetic fields are promoted for their physiological effects, while incidental fields from other therapeutic equipment are sometimes portrayed as inherently dangerous. The biological significance of each exposure has to be established through its physical characteristics and the research relevant to its intended use.
The experience with PEMF also illustrates why the word electromagnetic is too broad to serve as a meaningful description of biological risk. Two devices may operate at frequencies that fall within the same general category while producing very different exposure conditions and physiological effects.
The Biological Economy of Exposure
While writing Terrain 2.0: A Restoration Manual for the Modern Body, I spent considerable time examining the relationship between what supports biological function and what places additional demands on it. I began describing that relationship as the Biological Economy of Health, a framework for thinking about the cumulative effects of our environment, behavior, and recovery practices.
That perspective influences how I evaluate the technologies we use with athletes. I'm interested in the physiological response we're trying to produce, the conditions required to produce it, and the demands that an intervention may place on the body. Red light therapy belongs within that same evaluation because the potential benefits, limitations, and safety considerations all deserve to be understood.
We can investigate the clinical evidence for photobiomodulation, examine the optical performance of a device, and evaluate the electrical fields generated by its components. Each contributes different information to the overall assessment. There is currently no scientifically established method for subtracting a handheld EMF meter reading from a presumed therapeutic benefit and declaring the result a biological profit or loss.
I've worked with these technologies long enough to appreciate their potential, and I've spent enough time in the health and performance industry to recognize how quickly legitimate scientific concerns can become marketing opportunities. Manufacturers have every reason to compete on engineering quality, optical performance, transparent testing, and the reliability of their products. Consumers benefit when those claims are supported by measurements that can be independently examined.
The electromagnetic spectrum doesn't recognize marketing departments. The biological effects of exposure are governed by physical conditions and physiological responses, regardless of how a product is positioned or advertised.
The presence of an electromagnetic field is a measurement. It is not a diagnosis of biological harm.
Rocco Castellano is the author of Terrain 2.0: A Restoration Manual for the Modern Body and works in athletic performance, recovery, and restoration through PlayMakar Athlete Services.
This article is educational and does not replace medical advice or device-specific safety evaluations.
Scientific References
[1] National Institute of Standards and Technology (NIST).
Electromagnetic Spectrum Graphic. 2024.
https://www.nist.gov/image/electromagnetic-spectrum-graphic
[2] World Health Organization (WHO).
Extremely Low Frequency Fields. Environmental Health Criteria, Volume 238. 2007.
https://www.who.int/publications/i/item/9789241572385
[3] International Commission on Non-Ionizing Radiation Protection (ICNIRP).
Guidelines for Limiting Exposure to Time-Varying Electric and Magnetic Fields (1 Hz to 100 kHz). Health Physics. 2010;99(6):818–836.
https://pubmed.ncbi.nlm.nih.gov/21068601/
[4] International Agency for Research on Cancer (IARC).
Non-ionizing Radiation, Part 1: Static and Extremely Low-frequency Electric and Magnetic Fields. IARC Monographs, Volume 80. 2002.
https://publications.iarc.who.int/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Non-ionizing-Radiation-Part-1-Static-And-Extremely-Low-frequency-ELF-Electric-And-Magnetic-Fields-2002
[5] World Health Organization (WHO).
Extremely Low Frequency Fields. Environmental Health Criteria, Volume 238. 2007.
https://www.who.int/publications/i/item/9789241572385
[6] Hamblin, M. R.
Mechanisms and Applications of the Anti-inflammatory Effects of Photobiomodulation. AIMS Biophysics. 2017;4(3):337–361.
https://pubmed.ncbi.nlm.nih.gov/28748217/
[7] Quirk, B. J., & Whelan, H. T.
What Lies at the Heart of Photobiomodulation: Light, Cytochrome C Oxidase, and Nitric Oxide—Review of the Evidence. Photobiomodulation, Photomedicine, and Laser Surgery. 2020;38(9):527–530.
https://pubmed.ncbi.nlm.nih.gov/32716711/
[8] Maghfour, J., et al.
Evidence-based Consensus on the Clinical Application of Photobiomodulation. Journal of the American Academy of Dermatology. 2025;93(2):429–443.
https://pubmed.ncbi.nlm.nih.gov/40253006/
[9] International Electrotechnical Commission (IEC).
IEC 62471:2006 — Photobiological Safety of Lamps and Lamp Systems.
https://webstore.iec.ch/en/publication/7076
[10] U.S. Food and Drug Administration (FDA).
BIOMET EBI Bone Healing System — Premarket Approval Supplement P790002S026. 2011.
https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpma/pma.cfm?ID=P790002S026