What is Far Infrared?
Infrared (meaning below red) is a band of light that we can only perceive as heat or through technological advances. We can feel the effects of infrared light on our bodies. Similar to standing in the sun on a cold winter day, we feel warmer even though the temperature around us has not changed. Infrared Light represents approximately 49% of the light energy found on earth depending on a number of factors such as the amount of sunlight absorbed and the heat spent in evaporating water, temperatures on the surface of Earth vary somewhere between freezing and 90°F, which roughly defines the broad “spectrum” of infrared radiation emitted upward into the atmosphere. The Earths atmospheric infrared emission peaks at a wavelength of about 10 microns (micron is short for a micrometer or one millionth of a meter). Interestingly, the human body also absorbs and emits far infrared light at 10 microns.
How does far infrared light interact with the human body?
The human body is compose of varying percentages of water based on age. In a newborn infant, water volume may be as high as 75 percent of body weight, but it progressively decreases from birth to old age, most of the decrease occurring during the first 10 years of life. Also, obesity decreases the percentage of water in the body, sometimes to as low as 45 percent”. A healthy adult on average is approximately 60% water. Wikipedia
Far infrared radiation, has precisely the right energy to interact with water molecules present in the human body. When a special packet of light (called a photon) interacts with these water molecules, the molecules absorb the energy, and increases its temperature accordingly. It then re-radiates heat to its surroundings. When measured with an instrument, this absorbed heat forms absorption lines – (Any portion of the electromagnetic spectrum (including visible light) that is trapped by free atoms or molecules) the absorption line for the human body is approximately 10 microns.
This means that if the human body is hotter than its surroundings it emits more far infrared radiation than it absorbs, and tends to cool; if the human body is cooler than its surroundings it absorbs more radiation than it emits, and tends to warm. The human body will usually come to thermal equilibrium with its surroundings: a condition in which its rates of absorption and emission of radiation are equal.
Translation, the human body can only absorb so much far infrared light before it just passes on through and can no longer be trapped by our body.