9、 The difference between far infrared ray and near infrared ray(far infrared sauna), mid far infrared ray and other rays. The wavelength of near infrared ray is about 0.75-1.5 microns; The wavelength of mid infrared ray is about 1.5-4 microns; The wavelength of far infrared ray is about 4-1000 microns;
From this point of view(far infrared sauna), it is difficult for near and medium infrared rays to radiate through the atmosphere to the earth's surface, and they do not coincide with the wavelength of organisms. Their radiation energy is too strong. Like ultraviolet and microwave, they can destroy the molecular structure and are harmful to the human body. For example, Europeans are prone to skin cancer; Japanese people are prone to cataract. Thus, it is very important to protect the atmosphere and prevent ultraviolet radiation. Only far infrared ray is beneficial and indispensable radiant energy to human body.