Magnets are mostly physical magnets, which are harmful to human body. The sum of magnetic waves combined by two poles of traditional magnets presents a positive magnetic field effect, which is a kind of magnetic field pollution to health. A small magnet can attract nails a few centimeters away. The clock placed next to the magnet will affect the accuracy of walking time. Generally used small magnets, the magnetic induction intensity is not large, and it should have no serious impact on the human body. Strong magnetic radiation is harmful to human body. Magnets below 3000 gauss (magnetic field unit) will not cause harm to human body. Magnets with magnetic field strength above 3000 will do harm to human body.