Even a brief exposure to a high level of radiation could be dangerous.

Long-term exposure to low levels of radiation can also be dangerous.

Radiation is invisible and the effects may be gradual.
Beware !

A widespread radioactive hazard is presented by Radon gas.

Radon gas detectors are cheap and easy. Every home should have one.

Radioactive fallout does not respect national boundaries.

The wind can bring harmful materials anywhere.

Many of the hazards from a nuclear explosion are short-lived.

However, some hazards persist for a very long time.

We are all exposed to a certain level of radiation that we cannot avoid. This is called background radiation.


Sometimes we are exposed to higher levels of radiation, through things we do, or places we visit. There is also the concern that we might at some time be exposed to very high levels of radiation due to nuclear weapons or an accident at a nuclear power station.

Are you at risk from nuclear radiation?
To calculate your level of radiation exposure in a year. Click Dose.

What harm can radiation do?

Exposure to radiation can cause
loss of hair
skin burns
genetic defects (mutations)

What safety precautions are recommended?
The two most important issues for safety are

the wearing of protective clothing
and minimising the amount of exposure to the radiation

People who work with radioactive materials wear radiation badges. These badges contain film that is sensitive to radiation. the film is developed to show how much radiation the person has been exposed to.

Natural radioactivity

This, in general, does not present a danger. Background radiation due to cosmic radiation in space and due to radioactive substances like Uranium in the soil give rise to low levels of radiation that do not cause damage to health. Radon gas is one example of natural radioactivity that could present a health risk. For more information on the danger of Radon click here.

Artificial Radioactivity
This takes a number of different forms many of which could involve danger.
Many artificially produced radioactive isotopes are used in Industry and in Medicine. These could present a risk to those who use them.

What is radioactive fallout?

This is where radioactive particles are deposited on the surface of the Earth after they had been released into the atmosphere either by nuclear weapons or by discharge from a nuclear power station.

When a nuclear weapon is exploded close to the Earth's surface, a fireball develops. Inside the fireball and stem of the bomb cloud the radioactive particles become attached to heavier particles. These heavier particles then act as ballast.The heavier bits of matter fall back to earth within minutes, forming an extremely localized fallout, which is called fallback. Less massive but easily visible particles, carried downwind by the bomb cloud, fall within several hours, and are referred to as local fallout. The extent of local fallout depends on the size of the explosion, where it happened and the strength and direction of the winds. Microscopic particles stay aloft for longer periods of time. This is called global fallout. These particles may remain there for considerable periods of time.

Within the first hour after the explosion, most of the extremely short-lived substances (half-lives, measured in seconds or minutes) decay, and the total radioactivity from the bomb decreases more than a hundredfold. Most of the remaining radioactivity is due to fission products with long half lives like strontium-90 which has a half-life of 28 years. These long-lived species constitute the long-term radiation hazard. Long-lived radionuclides, such as strontium-90 may exist for many years as a potential hazard, primarily through contamination of the foods that are consumed by humans.

Although radioactive iodine-131 is extremely short-lived (half-life, eight days), it can cause serious damage to the thyroid gland. Soon after a nuclear accident, grass, which has been contaminated with iodine-131 is consumed by cows. The radioactive iodine then appears in their milk, which is usually consumed within a few days of production. When large amounts of radioiodine accumulate in the thyroid, it may result in thyroid cancer.

More Information

Radiation Protection Ireland
Radiation safety
FAQ on safe dose of radiation