Infrared is widely used but is it safe?

The safety of biomedical applications of far-infrared radiation can be reasonably assured only in so far as its thermal effects are concerned. However, no such assurance exists as to the non-thermal effects of not only far-infrared radiation but also of microwaves and radiowaves. The main applications of far-infrared radiation to biomedical engineering include infrared thermography, spectroscopy, and physical therapy. In all these applications, it is essential to know the penetration characteristics of far infrared radiation into biological tissue. The degree to which the far-infrared radiation penetrates the human body is intimately related to its heating effects, because the radiation's penetration depends on the extent to which the body's tissues absorb the radiation, converting it to heat.