Radio waves and microwaves are forms of electromagnetic energy that are collectively described by the term "radiofrequency" or "RF." Radiofrequency ranges from 9 KHz to 3000GHz. Radiation is defined as the propagation of energy through space in the form of waves or particles. Electromagnetic "radiation" can best be described as waves of electric and magnetic energy moving together (i.e., radiating) through space. There are two types of radiation on the basis of Ionization characteristics:
Ionizing Radiation - Radiation that is capable of ionizing atoms and breaking chemical bonds. e.g. X-rays, gamma rays.
Non-Ionizing Radiation - Radiation which is incapable of ionizing atoms and molecules such as RF waves.
It has been known for many years that exposure to high levels of RF radiation can be harmful due to the ability of RF energy to heat biological tissue rapidly. This is the principle by which microwave ovens cook food, and exposure to very high RF power densities, i.e., of the order of 100mW/cm2 or more, can clearly result in heating of biological tissue and an increase in body temperature.
Keeping this in view, the Ministry of Information Technology, Pakistan has adopted the International Commission on Non-Ionizing Radiation Protection (ICNIRP) Guidelines for public and professional exposure to radiation. These guidelines define the maximum permissible exposure in terms of Electric and magnetic field strengths and other technical parameters for different frequency ranges.