The intensity of electromagnetic radiation and national standards
According to the concept of electromagnetic radiation, it is known that electromagnetic radiation is actually a type of energy, and its impact on the environment mainly depends on the strength of the energy. The dimensional units of its intensity mainly include power density, electric field strength, and magnetic induction strength
Power density: refers to the high-frequency electromagnetic energy received or emitted per unit time and per unit area, measured in watts per square meter (W/m2). When evaluating high-frequency electromagnetic radiation environments, power density is commonly expressed in microwatts per square centimeter (μ W/cm2).
Induction intensity: Refers to the magnetic flux per unit volume or area, used to describe the intensity of energy in a magnetic field, measured in Tesla or Gauss (T or Gs).
The biological effects caused by electromagnetic radiation energy are related to the intensity of electromagnetic radiation, irradiation time, frequency of radiation waves, and physical length of biological exposure.
In order to control the pollution of electromagnetic waves to the environment, protect people's health, and promote the development of electromagnetic technology, China has formulated the National Environmental Electromagnetic Wave Health Standards of the People's Republic of China and GB9175-88. Usually, electric field strength V/m and power density μ W/cm2 are used as units.
The Chinese government has always attached great importance to public safety and has issued the Electromagnetic Radiation Protection Regulations (GB8702-88). The electromagnetic radiation limit standard of this regulation is much stricter than the international standard (see Table 1, usually used in the RF band), and the standard limit is determined to be 40 μ W/cm2.
Internationally, the radiation limit standard for the power frequency band (i.e. frequency 50Hz) is usually set at 0.4 micro Tesla (μ T).
It is known that the public radiation limit standard in China is only 40 μ W/cm2, which is more than 10 times stricter than the standards of the International Committee on Non Ionizing Radiation and EU countries, and 5 times stricter than the standards of Australia.
