Hazards and uses of radioactive emissions and of background radiation

Background radiation comes from

* natural sources such as rocks and cosmic rays from space
* man-made sources such as the fallout from nuclear weapons testing and nuclear accidents.

Half live

The time taken for the activity or count rate to half

Quicker half life is

More dangerous as more energy is released quicker

Nuclear radiation are used in medicine

* exploration of internal organs - medical tracer
* control or destruction of unwanted tissue - radiotherapy