Some heaters are marketed as ‘far infrared’. There is no agreed scientific definition of what the ‘far infrared’ range is, but it is certain that the heaters produce very long wavelengths of infrared (in the range 7,000 to 15,0000nm). We have seen some highly misleading and inaccurate claims about so-called far infrared heaters, which attribute to them exactly the same benefits as are obtained with shortwave infrared heaters, including an ability to heat objects and people without heating the air and provide effective absorption of infrared into skin tissue. This is impossible. In reality all long wavelengths of infrared transmit heat by warming the air. There is no equivalent form of warmth in the natural world, and the only sources of far infrared on earth are entirely man-made. Experts have raised concerns about the safety of far infrared heat sources. In her paper ‘Radiation effects on the eye, Part 1 – Infrared effects on ocular tissue’ (Optometry Today, May 1999), Dr. Janet Voke states that the infrared band IR-C (3000-10000nm) ‘does not normally reach the earth’s surface because it is absorbed by the atmosphere, but non-natural sources of IR-C can be a significant hazard’ (para. 2). We do not sell these.