Nuclear radiation can damage or destroy living cells or make cells grow abnormally causing cancer.
The most dangerous is radiation caused by radioactive materials absorbed by the body. Radioactive gas and dust may be taken into the body along with air, food or drink. Once absorbed, they are difficult to remove and cause damage to the cells. Inside the body, alpha radiation is the most dangerous because it is highly ionising.
There is lesser risk from radioactive sources outside the body. The intensity of the radiation decreases with distance from the source. Outside the body, beta and gamma radiations are more harmful as they can penetrate internal organs, while alpha particles can be stopped by the skin.
Sources of Nuclear radiation:
There is a small amount of radiation around us all the time that comes from natural sources like soil, rocks, air,building materials, food and drink, space.
The biggest single source of natural background radiation is from a radioactive gas called radon which seeps out of rocks.
The biggest source of artificial radiation if from medical X-rays. A small portion comes from radioactive waste from nuclear power stations and radioactive fallout from nuclear weapons testing.
A Geiger-Muller tube is used to detect radiation.