Electromagnetic radiation is the radiation generated to the surrounding space by electromagnetic waves due to alternating electric and magnetic fields. Due to the low energy of this type of radiation, it cannot cause ionization of the surrounding material. Strictly speaking, all electrical appliances (including household appliances) will produce electromagnetic radiation, but will really cause environmental pollution affecting human health is some high-power communication equipment, such as radar, television and radio transmitters, industrial microwave heaters (household microwave ovens may also have electromagnetic radiation leakage), radio frequency induction and dielectric heating equipment, high-voltage power transmission and transformation equipment, electromagnetic medical and diagnostic equipment and so on. Because the nature of radiation is different, so it acts on the human body mechanism is also different from ionizing radiation. Electromagnetic radiation has a near-area field and far-area field, which is divided by a wavelength distance. Near-area field of electromagnetic field strength is much greater than the far-area field, so it is the focus of monitoring and protection.