Containing material is generally present excitation tritium

Containing material is generally present excitation tritium (3H or T), promethium (Pm) and radioactive radium sulfate (Ra) , fluorescent agents and fluorescent agents , mostly zinc sulfide, glow in the dark , calcium or zinc , and other alkylene sulfates. Tritium (3H or T) and promethium (Pm) , though still radioactive , but the potential damage to the human body is much smaller. Tritium (3H or T) is an isotope of hydrogen , the nucleus consists of a proton and two neutrons , with radioactivity occurs β decay half-life of 12.43 years . Although tritium (3H or T) material also manufacture thermonuclear gravel driveway , but its β decay will release the fast-moving electrons, does not penetrate the human body, only a lot of contact with and inhalation of tritium (3H or T) will cause the human body injury.