Elektromagnetic spectrum

The solar radiation, popularly know as sunlight,  is an electromagnetic wave including, among others, infrared rays. The infrared radiation passes throught the Earth's atmosphere, a part of it is absorbed while the rest reach the Earth's surface and heat it up. Therefore also the Earth's surface becomes an infrared radiator.

Ultraviolet radiation wawelenght:       < 38 µm.
Visible solar radion wawelenght:        = 0,38 - 0,78 µm.
Infrared radiation wawelenght:           > 0,78 µm.

The CLASSICtherm heating panel radiation range is equal to the wawelenght of the infrared radiation. They are radiating the heat on the same way as the Sun heats the Earth, therefore they have no harmful physiological effect.