What is FIR?
You might remember from your high school physics class that the sun is eight minutes from the earth at the speed of light. The sun is the source for most of our light, and it creates solar radiation. That radiation is electromagnetic, and it’s defined by wavelength.
The whole electromagnetic spectrum contains what we see (i.e., visible light), but it also contains six other components: radio waves, microwaves, infrared waves (IR), ultraviolet waves (UV), X-rays, and gamma rays. The wavelength for visible light falls between IR and UV. (1)
Our sensory systems process sunlight in several ways. Visible light is received by our eyes, converted to nerve signals, sent to the brain, and processed into images (i.e., interpreted and seen).
On the other hand, IR radiation cannot be seen. We have heat receptor cells in our skin that receive IR radiation, again sending information to the brain via our nerves. Then we interpret IR heat or warmth. UV radiation is not visible, and it’s only palpable when we get sunburned.
Radio waves, microwaves, X-rays, and gamma rays are also components of sunlight. These waves penetrate deep into our tissues and affect our tissues and innervation. We may be aware of a sense of vague pain, but the brain doesn’t know how to interpret deep-tissue damage. Each of these waves are defined by their wavelength.
Long waves lie below radio wavelengths. The wavelengths vary, getting dramatically smaller as the progress from radio waves to gamma waves. The wavelength of IR waves can range from 0.75 to 1,000 micrometers. (2)
The infrared spectrum is subdivided into Near-Infrared (aka NIR or IR-A), Short-Wavelength Infrared (aka SWIR or IR-B), Mid-Wavelength Infrared (aka MWIRm IR-C or MidIR), Long-Wavelength Infrared (aka LWIR or IR-C), and Far-Infrared (aka FIR) bands.
However, the wave definitions accepted by given scientists may differ by specific disciplines. The FIR component has the least energy. In terms of the earth’s reception of solar radiation, about half of the heat received from the sun is in the infrared spectrum. (3)
Wavelength is significant to this discussion. Ionizing radiation consists of atomic components that move at high rates and penetrate tissues. UV rays, X-rays, and gamma rays are included in the ionizing electromagnetic spectrum.
These parts of the spectrum are capable of causing changes in the DNA of our cells, altering cell survival (directly and indirectly). All cells are mostly comprised of water. Remember, a water molecule is made of two hydrogen atoms and one oxygen atom bound together. Ionizing radiation can break that bond, allowing those atoms to freely combine with other cell components and potentially form substances that’re toxic to the cell (e.g., hydrogen peroxide).
Since cells vary in composition and are deferentially affected by ionizing radiation, cells that are regenerating at faster rates are the most susceptible. Our most fragile cells are our lymphocytes and blood-producing cells, then our gastrointestinal and reproductive cells, and lastly, our muscles and nerve cells.(4)
How FIR Works
The electromagnetic spectrum below UV (e.g., visible light, IF, microwaves, and radio waves) is non-ionizing. (5)
Radio and microwave radiation cause molecules to vibrate and cause heat, but there isn’t the destruction associated with ionizing radiation. Cell phone towers, microwave ovens, and airport scanners are typical sources of this part of the non-ionizing spectrum. (6)
When energy is high enough to cause structural change to atoms, some parts of the UV spectrum have been shown to induce cancer, but visible light and IR waves are relatively benign, only causing heat with added intensity. (7)
Despite IR absorption into the skin and eyes, the Occupational Safety and Health Administration only notes that a sensation of heat or pain accompanies IR exposure. But in excess, visible light may induce eye or skin damage. (9)
FIR is the only component of IR that’s simple heat, and it’s perceived by thermal sensors in skin. It’s absorbed and reflected from the body when it’s been saturated with sufficient FIR to change our internal body temperature. Initially, a body will absorb all FIR, acting as a perfectly absorbing blackbodies—until it emits surplus energy as blackbody radiation. When absorbed, FIR alters cell membranes and mitochondrial metabolism, interacting with water molecules and proteins in the cell. (9)
FIR’s action is perceived as a gentle heat. Its radiant quality may penetrate an inch and a half into the skin. This energy causes molecular resonance that induces a prolonged rise in internal temperature, unlike heat generated by shorter wavelengths. Molecular resonance at deeper levels may occur without the surface skin showing any response. FIR may be generated by an active emitter. It may also be generated by the body producing its own energy as a passive emitter, or it may receive reflected energy. (10)
Damage to the eyes, the skin, and their substructures may occur with some laser radiation. If you avoid looking at IR lasers and respond to burning sensations delivered by laser, you can be proactive in self-protection from any thermal damage. (11)
History
Remember being reprimanded for being out in the sun too long and getting sunburned? Regarding UV protection, we have a general understanding that there’s something in sunlight that can cause problems. A lot of the knowledge base about this subject matter is relatively recent.
In fact, it was only a half century ago that we felt that sunlight and sun exposure were always healthy. People have been aware of light and the sun since creation, but it was only in the late 1600's that Dutchman Christiaan Huygens reported his research in Treatise on Light.
He proposed that light was a wave spreading from a source through a universe filled with ether. Then Isaac Newton wrote Opticks in the early 1700's. He experimented with telescopes and viewed color-spectrum components in the lenses. He concluded that what he saw were flaws in the glass. He concluded that the collection of colors were just components of light.
Robert Hooke argued with Newton, proposing that color was just a matter of intensity. The idea that the different colors represented those units also developed as Newton refined his concept of refraction and optics. 300 years later, Einstein would present his “quantum theory of light,” uniting wave and particle theory in a unified light concept. (12,13>)
Other theories in electromagnetic radiation are relevant to the history of FIR waves. William Herschel measured the heat component of the various colors in the light spectrum in 1800, essentially discovering infrared light. Johann Wilhelm Ritter identified the UV portion of the spectrum in 1801.
James Clerk Maxwell predicted wavelengths beyond IR, confirmed in 1887 by Heinrich Hertz’s production of radio waves. In 1895, Wilhelm Conrad Roentgen discovered X-rays at the other end of the electromagnetic spectrum. In his studies of radium, Paul Villard discovered gamma rays in 1900. The relationship of X-rays and gamma rays to the light spectrum were confirmed in 1912 and 1914, respectively. (13)
In summary, our current theory of light and its spectrum components suggests that electromagnetic waves are arranged by wavelength and frequency. These energy waves travel at the speed of light. (14)
In terms of the discovery of IR components, the divisions of IR and the positioning of FIR within IR have been defined by convention, not by a specific person. (15)
Specific FIR sources for study are inequivalent, but they do follow certain international standards. In the United States, the Department of Health and Human Services’ Food and Drug Administration has standard jurisdiction. A sample of its oversight for FIR generators is provided in this link to its evaluation of Infrared Heating Device Model PM-750. (16)
Science-Backed Wellness Benefits
Temperature Increases in the Tissues and Motility of Body Fluids
In a 1989 report, the efficacy of the placement of small, ceramic disks (either placed locally or on the whole body) demonstrated that “far-infrared rays are biologically active.” In fact, they promoted growth in young rats and the modulation of sleep in free rats.
A man with insomnia had a similar response, and his skin showed enhanced blood circulation. A questionnaire administered to 542 users of FIR radiator disks buried in sheets, blankets, and pillows revealed subjective wellness improvements. The presumed action appeared to be produced by the increase of temperature in tissues and the enhanced movement of body fluids (due to the reduction of cellular water clusters). (17)
FIR Laser Devices Are Mostly Benign, but Short-Wavelength Infrareds Aren’t
A 1998 report revealed that infrared laser devices could damage the retinas (but not other tissues). Other IR devices demonstrated a greater possibility of tissue damage. Plastic goggles attenuated damage and were tunable to wavelengths. (18)
In a 2003 report, an infrared massage device was associated with accidental burns. (19) And in a 2005 report, optical instrumentation employing infrared radiation was adjusted to enhance protection. (20)
Vascular System Shows Improvement with FIR
In a 2001 report, 25 men with coronary risk factors (e.g., diabetes mellitus, hypercholesterolemia, hypertension, and smoking) and 10 men without these factors were treated with FIR. Dilation measures are also improved by FIR sauna therapy.
In a 2001 hamster study, their blood flow revealed improved aortic blood flow with sauna treatment. (21)
Short-Term Relief for Rheumatoid Arthritis and Ankylosing Spondylitis
In a 2009 report, 17 subjects with rheumatoid arthritis and 17 others with anklyosing spondylitis underwent a four-week period of eight IR treatments. Short-term relief from pain and stiffness were noted, as well as a reduction in fatigue. (22)
Sun-Spectrum Skin Muscle Damage Can Be Induced by IR
In a 2010 report, studies in rats using sun-spectrum IR radiation showed long-term mid-tissue muscle damage from exposure. FIR was not differentiated from other IR sub-bands, so evidence for FIR-induced muscle thinning was not confirmed.(23)
FIR Has Been Found to Be Biologically Safe
FIR was investigated on biological effects in 2012, and cell stimulation with FIR was shown to be safe in certain conditions. Focused technology (e.g., using lamps and sauna) produced FIR radiation directed at the body.
Therapeutic results were described as “safe, effective, and widely used.” Using of ceramic nanoparticles within fabrics to emit FIR also brought wellness benefits. The presumed mechanism was radiant heat externally and blackbody heat internally. (24)
FIR Reduction of Post-Op Pain
In a study reported in 2012, 41 subjects were allocated to a study or control group, half of which were exposed to five days of FIR therapy via pads applied to specific points.
They concluded that pain and discomfort (when measured subjectively and objectively) were ameliorated with FIR. (25)
FIR Stimulation Mitigates Some Ischemic Damage
HO-1 is part of the body’s hypoxia-protection system. In a 2013 report, researchers used FIR stimulation to heat tissues for 30 minutes (after they induced tissue damage).
Tissue levels of HO-1 was inversely related to cellular apoptosis. A control group with non-FIR tissue heating showed greater damage. Researchers concluded that FIR radiation after ischemia onset attenuated injury. (26)
FIR Impacts Neck and Arm Pain
In a 2014 report, 48 patients with chronic myofascial neck pain were included in a double-blind study. In it, subjects wore a ceramic FIR device for a week. Then they were measured for pain, sleep quality, muscle tone, and skin temperature.
Trapezius muscle stiffness was decreased in the experimental group, but all other measures revealed no significant difference between study groups. (27) Also, in a 2014 report, 600 subjects with carpal tunnel syndrome received FIR sauna treatment (with 70% finding relief). (28)
The Influence of FIR on Endothelial Progenitor Cells
According to a 2015 report, the repair of the vascular system is facilitated by endothelial progenitor cells. When diabetes is present, cell repair fails, but FIR therapy promoted this repair.
Failing cells were FIR-stimulated and evaluated. Enhanced repair was observed on the genetic level, suggesting a management strategy for diabetes-related ischemia and metabolic-related cardiovascular problems. (29)
FIR-Enhanced Blood Flow in Hemodialysis Patients
In a 2016 report, researchers noted that arteriovenous-fistula failure in hemodialysis patients had major impacts on their well-being. Fewer adverse effects were noted, while arteriovenous graft patency was enhanced. (30)
In another 2016 report, 25 outpatients on chronic dialysis were matched to a control group. FIR was administered several times a week for 12 months in 40-minute doses. Measurements showed enhanced blood flow in patients by the third month. (31)
FIR Suppression of Skin Aging
In a 2017 report about studies on mice, FIR was found to minimize UV effects on skin by increasing procollagen and autophagy and inhibiting UV-induced changes. Skin thickness and the degradation of collagen fibers was reduced. (32)
FIR for Damaged Lymph Nodes
In a 2017 report, 32 patients with lymphedema were treated with FIR and evaluated for fluids, fats, and proteins in swollen tissues, and the swelling decreased in all of them. Post-treatment limb circumference decreased, and quality of life increased. Researchers concluded that FIR was “both an alternative monotherapy and a useful adjunctive to conservative or surgical lymphedema procedures.” (33)
Precautions
Our discussion has involved FIR and its part of the electromagnetic wave spectrum. Even normal sunlight contains components that compromise our wellness. FIR belongs to non-ionizing wavelengths, along with other IR wavelengths. FIR differs from other IR waves: it has less power and is unable to deeply penetrate our body's tissues.
FIR may be included with other spectra from the IR range, depending on the radiation source. This finding is significant because non-FIR IR radiation may do bodily damage due to the generation of heat; the deeper tissues of the body aren’t as sensitive to heat damage. We can feel potential FIR damage occurring because our thermal sensory system is in our skin.
The FDA has approved FIR devices that appear to be safe. Each device differs from others by materials used in construction, by power level, and by ability to conform in some way to the body. Therefore, the manufacturer data provided to the FDA should be your guide while purchasing. Wattage and voltage are not the factors to evaluate; rather, check the IR bandwidth and suggested dosage of the device.
A suggested FIR heat range of 7 to 11 microns has been suggested. Devices differ, but so do our bodies. Talk with your healthcare provider about your desire to use a FIR device. Your wellness complaints, joint problems, medications, gender, and implants will all determine whether a device is right for you. Above all else, safeguard your eyes, use your device for its intended purposes, listen to your body, and promptly discontinue use as needed.
Various materials have been incorporated into beds, ceramics, lamps, compressions, enclosures, wraps, mats, saunas, and clothing. If these devices are simply labeled as IR devices, they may not be suitable for your use. The broad IR wave band includes deep-tissue heat radiation, which is capable of tissue damage.
Conclusion
As a civilization, we have given up hard-copy publications and become more and more dependent on the internet for our information. Unfortunately, we still need scientific data that’s traceable to formal, peer-reviewed studies.
And it should be reported in reputable journals with a robust readership capable of challenging data reliability. Also, remember that the language barrier can muddy the waters. Bottom line: don't be quick to accept a claim, or fail to fully consider its content and probability.