Radiation Types, Effects, Hazards & Control Measures

Radiation is a type of energy that travels through the air and can be absorbed by living things. It comprises tiny particles called photons, released when an atom decays or becomes unstable. Radiation can harm living things but can also be used for beneficial purposes, such as in medical imaging and cancer treatment.

There are two main types of radiation: ionizing and non-ionizing. Ionizing radiation has enough energy to remove electrons from atoms, which can damage cells and lead to cancer. Non-ionizing radiation does not have enough energy to cause this damage, but it can still be harmful if it is intense enough or if the body absorbs it over a long period.

Radiation is all around us, but it is not always dangerous. The sun emits ultraviolet radiation that can cause sunburn, but it also gives us vitamin D and helps us stay warm. Cell phones emit non-ionizing radiation, but their amount is very small and is not known to be harmful.

There are some situations where radiation can be dangerous, such as when someone is exposed to a large amount of radiation all at once (known as acute exposure), or when someone is exposed to lower levels of radiation over a long period (known as chronic exposure). Acute exposure can occur during a nuclear accident, while chronic exposure can occur from living near a nuclear power plant or working with radioactive materials. This blog post will discuss the types of radiation, its effects, hazards and the control measures associated with radiation.

Types Of Radiations & Their Applications

There are three types of radiations: alpha, beta, and gamma. Each has unique properties and uses.

Alpha radiation is the least penetrating of the three types of radiation. It comprises two protons and two neutrons bound together into a particle identical to a helium nucleus. Alpha particles are emitted from the nuclei of some radioactive atoms as they decay.

Beta radiation is more penetrating than alpha radiation, but not as much as gamma radiation. It is made up of either an electron or a positron (the antimatter counterpart of an electron). Beta particles are emitted from the nuclei of some radioactive atoms as they decay.

Gamma radiation is the most penetrating of the three types of radiation. It is a form of electromagnetic radiation, like X-rays. Gamma rays are emitted from the nuclei of some radioactive atoms as they decay.

There are many uses for radiation, both in medicine and industry. Radioactive isotopes are used in medical procedures such as PET scans and cancer treatments. They are also used in industrial processes like smoke detectors and radiotherapy.

Alpha radiation is used in smoke detectors. The alpha particles emitted by a radioactive isotope are detected by a sensitive detector. When smoke enters the detector, it absorbs some alpha particles, which triggers an alarm.

Beta radiation is used in cancer treatment. Beta particles can be directed at cancerous tissue, where they destroy the DNA and cause the cancer cells to die.

Gamma radiation is used in PET scans. A PET scan uses gamma rays to create images of the inside of the body. The gamma rays are emitted by a radioactive isotope and detected by a special camera.

Radiation can also be used for research purposes. For example, scientists use particle accelerators to study the properties of subatomic particles. Radiation is a powerful tool that can be used for both good and bad purposes. It is important to understand the risks and benefits of radiation before using it.

Ionising Radiation

Ionising radiation is emitted from radioactive materials, either directly ionising alpha and beta particles or indirectly ionising X-rays, gamma rays, or neutrons. It has a high energy potential and an ability to penetrate, ionise and damage body tissue and organs.

All matter consists of atoms, a nucleus containing protons and neutrons, and orbiting electrons. The number of protons within the atom defines the element – for example, hydrogen has 1 proton, and lead has 82 protons. Some atoms are unstable and will change into atoms of another element, emitting ionising radiation. The change is called radioactive decay, and the ionising radiations most commonly emitted are alpha and beta particles and gamma rays. X-rays are produced by bombarding a metal target with electrons at very high speeds using high-voltage electrical discharge equipment. Neutrons are released by nuclear fission and are not normally found in manufacturing processes.

Alpha particles consist of two protons and two neutrons and have a positive charge. They have little power to penetrate the skin and can be stopped using flimsy material, such as paper. Their main route into the body is ingestion.
Beta particles are high-speed electrons whose penetration power depends on their speed, but penetration is usually restricted to 2 cm of skin and tissue. They can be stopped using aluminium foil. There are normally two routes of entry into the body – inhalation and ingestion.
Like X-rays, Gamma rays are electromagnetic radiation and have far greater penetrating power than alpha or beta particles. They are produced from nuclear reactions and can pass through the body.

The two most common measures of radiation are the Becquerel (Bq), which measures the activity of a radioactive substance per second, and the Sievert (Sv), which measures the biological effects of the radiation – normally measured in milliSieverts (mSv).

Thus, the Becquerel (Bq) measures the amount of radiation in a given environment, and the milliSievert (mSv) measures the ionising radiation dose received by a person. Ionising radiation occurs naturally from man-made processes, and about 87% of all radiation exposure is from natural sources.

Harmful Effects Of Ionising Radiation

Ionising radiation attacks the body’s cells by producing chemical changes in the cell DNA by ionising it (thus producing free radicals), which leads to abnormal cell growth. The effects of these ionising attacks depend on the following factors:

The size of the dose – the higher the dose then, the more profound will be the effect;
The area or extent of the exposure of the body – the effects may be far less severe if only a part of the body (e.g. an arm) receives the dose;
The duration of the exposure – prolonged exposure to a low dose is likely more harmful than a short exposure to the same quantity of radiation.

Acute exposure can depend on the dose size, blood cell changes, nausea and vomiting, skin burns and blistering, collapse, and death. Chronic exposure can lead to anemia, leukaemia and other forms of cancer. It is also known that ionising radiation can have an adverse effect on the function of human reproductive organs and processes. Increases in the cases of sterility, stillbirths and malformed foetuses have also been observed.

The health effects of ionising radiation may be summarised into two groups – somatic results, which refer to cell damage in the person exposed to the radiation dose and genetic influences, which refer to the damage done to any future children of the irradiated person.

Sources Of Ionising Radiation

The principal workplaces that could have ionising radiation are the nuclear industry, medical centres (hospitals and research centres) and educational centres. Radioactive processes are used for the treatment of cancers, and radioactive isotopes are used for many different types of scientific research. X-rays are used extensively in hospitals, but they are also used in the industry for non-destructive testing (e.g. crack detection in welds). Smoke detectors, used in most workplaces, also use ionising radiations.

Ionising radiations can also occur naturally – the best example is radon, a radioactive gas that occurs mainly at or near granite outcrops where there is a presence of uranium. It is particularly prevalent in Devon and Cornwall. The gas enters buildings normally from the substructure through cracks in flooring or around service inlets.

The Ionising Radiations Regulations have set two action levels above which remedial action, such as fitting sumps and extraction fans, has to be taken to lower the radon level in the building. The first action level is 400 Bq/m3 in workplaces and 200 Bq/m3 in domestic properties. At levels above 1000 Bq/m3, remedial action should be taken within one year. The average background radiation in the UK is 2.4 mSv per year. Background radiation levels are much higher worldwide – 260 mSv have been recorded in Iran.

About half of the background radiation in the UK is caused by radon. Radon gas is responsible for 5% of lung cancer cases. Radon is not generally a problem unless it can accumulate in confined spaces such as basements, cellars or lift shafts. An impermeable membrane beneath the floor can be laid to prevent the gas from entering the building through the floor. This latter treatment usually is only suitable for new buildings but does cost less than 10% of the cost of a sump and has no running costs. There are now government-defined ‘radon-affected areas’ throughout the UK, so checks should be made if underground spaces in buildings are to be used. About 14% of exposures to ionising radiation are due to medical exposures during diagnostic or treatment processes.

The hazards are categorised as either stochastic or non-stochastic. The principal stochastic hazard is cancer in various forms. The main nonstochastic effects include radiation burns, sickness, cataracts and damage to unborn children.

Personal radiation exposure can be measured using a film badge, which the employee wears over a fixed time interval. The badge contains a photographic film developed after the interval, and an estimate of radiation exposure is made. A similar device, known as a radiation dose meter or detector, can be positioned on a shelf in the workplace for three months to measure the mean value of radiation levels. Instantaneous radiation values can be obtained from portable hand-held instruments, known as Geiger counters, which continuously sample the air for radiation levels. Similar devices are available to measure radon levels.

Non-ionising Radiation

Non-ionising radiation includes ultraviolet, visible light (lasers that focus or concentrate visible light), infrared and microwave radiation. As the wavelength is relatively long, the energy present is too low to ionise atoms which make up matter. The action of non-ionising radiation is to heat cells rather than change their chemical composition.

The Control of Artificial Optical Radiation at Work Regulations govern non-ionising radiation. The Personal Protective Equipment at Work Regulations is also relevant since skin or eye tissue burning is the most significant hazard.

Ultraviolet radiation (UV) occurs with sunlight and with electric arc welding. In both cases, the skin and the eyes are at risk from the effect of burning. The skin will burn (as in sunburn), and repeated exposure can lead to skin cancer. Skin exposed to strong sunlight should be protected by clothing or sun creams. This problem has become more familiar with the reduction in the ozone layer (which filters out much ultraviolet light). The eyes can be affected by conjunctivitis, which feels like grit in the eye, and is called various names depending on the activity causing the problem. Arc welders call it ‘arc eye’ or ‘welder’s eye’ and skiers’ snow blindness. Cataracts caused by the action of ultraviolet radiation on the eye lens are another possible outcome of exposure.

The most dangerous form of skin cancer, malignant melanoma, has increased by over 40% over the last ten years, making it cancer with the fastest rising number of cases in the UK. Outdoor workers that could be at risk include farm or construction workers, market gardeners, outdoor activity workers and some public service workers. Those who are particularly at risk have:

fair or freckled skin that does not tan or goes red or burns before it tans;
red or fair hair and light-coloured eyes;
a large number of moles.

Employers must be aware of their employees’ risks when working outside without adequate sun protection. With growing concern following the rise in skin cancers, the HSE has suggested the following hierarchy of controls for outdoor working:

relocate some jobs inside a building or to a shady location;
undertake some outdoor work earlier or later in the day;
provide personal protection such as: wearing long sleeve shirts or loose clothing with a close weave; wearing hats with a wide brim; using a high factor sunscreen of at least SPF15 on any exposed skin;
provide suitable education and training for outdoor workers;
Provide suitable information and supervision to instigate safe systems of work that protect workers from the sun.

UV radiation has beneficial effects, such as accumulating vitamin D and strengthening bones.

Where UV interlocutors are used, generally in kitchens, to control flying insects, the correct emitting labels must be fitted and not ones that, for example, are used to sterilise surgical instruments, as has happened on one occasion.

Lasers use visible light and light from the invisible wavelength spectrum (infrared and ultraviolet). As the word laser implies, they produce ‘light amplification by stimulated e mission of r radiation. This light is highly concentrated and does not diverge or weaken with distance. The output is directly related to the chemical composition of the medium used within the particular laser. The output beam may be pulsating or continuous depending on the laser’s task. Lasers have extensive applications, including bar code reading at a supermarket checkout, metal cutting, and welding, and accurate measurement of distances and elevations required in land and mine surveying. They are also extensively used in surgery for cataract treatment and the sealing of blood vessels.

The International Electrotechnical Commission (IEC) and the American National Standards Institute (ANSI) have defined seven classes of laser (1, 1M, 2, 2M, 3R, 3B and 4) in ascending size of power output. Classes 1, 1M, 2, and 2M are relatively low hazards and only emit light in the visible band. Direct eye contact must be avoided in classes 3R, 3B and 4. These are more hazardous than classes 1 and 2; a laser safety officer appointment is recommended. A Class 4 laser can burn the skin and cause permanent eye damage due to direct, diffuse or indirect exposure to the beam. Such Class 4 lasers can ignite combustible materials and are a fire risk. All lasers should carry information about their class and any precautions required.

The main hazards associated with lasers are eye and skin burns, toxic fumes, electricity, and fire. The vast majority of accidents with lasers affect the eyes. Retinal damage is the most common and irreversible. Cataract development and various forms of conjunctivitis can also result from laser accidents. Skin burning and reddening (erythema) are less common and are reversible.

Infrared radiation is generated by fires and hot substances and can cause eye and skin damage similar to that of ultraviolet radiation. It is a problem for firefighters and those working in foundries or near furnaces. Eye and skin protection are essential.

Microwaves are used extensively in cookers and mobile telephones, and there are ongoing concerns about associated health hazards (and several inquiries are currently underway). The severity of any hazard is proportional to the power of the microwaves. The principal hazard is heating body cells, particularly those with little or no blood supply, to dissipate the heat. This means that tissues such as the eye lens are most at risk from injury. However, it must be stressed that the chances are higher for items such as cookers than for low-powered devices such as mobile phones. The measurement of non-ionising radiation typically involves the determination of the power output being received by the worker. Specialists in the field best perform such surveys, as interpreting the survey results requires considerable technical knowledge.