Radiation and Daily Life

Measures how much
radiation is emitted by a radioactive material
Measures the radioactive energy absorbed by the unit mass of a substance
Measures the health
impact of exposure to
ionising radiation

While many people worry about radiation, it is in fact part of our daily lives. The earth is naturally radioactive, so is the air we breathe, the food we eat and the ground we stand on!

Radiation then need not be something we should be afraid of. It benefits us and our society in many different ways. One of the most commonly recognised examples is medical applications such as the X-rays and Positron Emission Tomography (PET) scans doctors use to provide images that identify abnormal changes in our body organs and tissues. In therapeutic treatments, radiation is used to destroy cancer cells. Apart from medicine and electricity generation, other common usage of radiation also include industrial, agricultural and consumer product applications, examples include quality control systems, insect extermination, smoke detector and lightning conductor.

A radioactive material will release energy overtime and therefore steadily reduce its level of radioactivity. The rate of reduction in its radioactivity level is measured by its “half-life”. A short half-life means that the radioactive material decays rapidly by releasing more energy within a particular time frame.

Half-life of Radionuclide
Type of radiation Radionuclide Half-life Type of radiation Radionuclide Half-life
α Ununoctium-294 ~ 0.89
β Strontium 90 28.8 years
α Radon-219 4 seconds β Caesium-137 30 years
α Copernicium-285 34 seconds α Radium-226 1,600 years
N/A* Potassium-38 7.6 minutes β Carbon-14 5,730 years
N/A* Selenium-73 7.2 hours α Plutonium-239 24,100 years
β Xenon-133 5.25 days β Iodine-129 15,700,000 years
β, γ Iodine-131 8 days α Uranium-235 703,800,000 years
β, γ Cobalt-60 5.26 years β Potassium-40 1,277,000,000 years
β Tritium (Hydrogen-3) 12.32 years
* This radionuclide will experience changes and release energy after absorbing electrons (electron capture)
Source: Hong Kong Observatory; Bureau International Des Poids et Mesures 2008; Encyclopedia Britannica; Physical Review C 74, 044602 (2006) American Physical Society