- What is it?
- What it does?
- Where does it come from?
- Why is it harmful in some cases?
1. outer space
2. the Earth
3. the air we breathe
4. the food and drink we take
5. man-made sources
Ionizing and Non-Ionizing Radiation
- gamma rays
- alpha particles
- beta particles
- and cosmic rays
Non-ionizing radiation is radiation without enough energy to ionize the atoms. Examples of this radiation and devices using it are:
- visible light
- radio frequency
- extremely low frequency
- and ultrasound
Natural and Artificial Radiation
Radioactive material is found throughout nature. It occurs naturally in soil, water, and vegetation. All living things are constantly bombarded by radiation from space known as cosmic radiation. Everyone has radioactive materials inside their bodies from birth.
Radiation can also be produced artificially by humans. For example, X-rays in hospitals are produced electrically without using radioactive substances. The same is true for radio waves that transmit our radio and TV programs through the air.
Radiation side effects on health
British estimates on radiation side effects
- Lower levels of psychological well-being which includes depression, anxiety, self-harm and suicide.
- Higher rates of morbidity, for example, debilitating long-term illness.
- Higher rates of premature deaths, especially coronary heart disease, injuries and poisoning, including suicide.
Australian estimates on radiation side effects
- 10,000 mSv (10 Sieverts) as a short-term and whole-body exposure would cause immediate illness such as nausea and decreased white blood cell count. It will cause subsequent death within a few weeks.
- 1,000 mSv (1 Sievert) in short-term dose causes immediate radiation sickness. Above 1,000 mSv, the severity of illness increases with dose. If exposure greater than 1,000 mSv occur over a long period, they pose a definite risk of cancer in later years.
- Above about 100 mSv, the probability of cancer increases with dose. The estimated risk of fatal cancer is 5 of every 100 persons exposed to a dose of 1,000 mSv. If the normal incidence of fatal cancer were 25%, this dose would increase it to 30%).
- 50 mSv is the highest expsoure allowed by regulation in any one year of occupational exposure.
- Approximately 2 mSv a year is the typical background radiation from natural sources, including an average of 0.7 mSv per year from radon in air. This is close to the minimum dose received by all humans anywhere on Earth.
- 0.3-0.6 mSv a year is a typical range of dose rates from artificial sources of radiation, mostly medical.