The subway has no radiation, but there is radiation through the security check. Pregnant women can ride.
The radiation from the security check is very small, almost negligible.
From more specific data, according to the "ionizing radiation protection and radiation source safety basic standards", the normal person shall not receive radiation dose of more than 1mSv per year.
National standard GB 15208.1-2005 provides that the X-ray security checker single check dose should be <5?Gy, at a distance of 5cm from the outer surface of the equipment at any place (including equipment)
The X-ray screening equipment used in the subway, the single inspection dose of 0.534?Gy, 5cm from the outer surface of the radiation dose of 0.788 μGy/h, about 1/10 of the upper limit of the national standard.
According to the data reported by the United Nations Scientific Committee on the Effects of Radiation, the radiation dose of a medical X-ray chest X-ray is 50?Gy. That is to say, even if a person is really put inside this X-ray screening machine, it takes about 100 scans to reach the radiation dose received by a chest X-ray.
Extended information:
The X-rays used by the security checker belong to the ionizing radiation, nature's ionizing radiation is ubiquitous, and usually drink the water, breathe the air with this radioactive elements, these elements constitute our living environment, "it can be said that the people live in the sea of rays ".
The radiation produced by the subway security check is very small and does not cause direct harm to people. Due to the small amount of radiation generated, and rays in the machine inside the vertical irradiation, the shell has a layer of shielding, coupled with people just a short stay, so do not have to worry about radiation.
Passengers usually go through just its metal shell, these devices in normal use, will not cause physical harm to the environment and the public passing nearby, passengers normally through the security checker, do not have to be too much panic.
Reference? People's Daily Online - subway security radiation harmful to health? Experts: radiation is small need not worry