What is radiation?

Radiation is energy that travels through space or a material medium in the form of waves or particles. It surrounds us at all times, from the warmth of the sun on our skin to the signals that carry our mobile phone calls. While radiation can sound alarming, it plays a vital role in modern life, powering medical imaging, treating cancer and enabling electricity generation. Understanding what radiation is, how it behaves, where it comes from and how we can protect ourselves helps us make informed choices and reduces unnecessary fear.

What is radiation?
At its simplest, radiation involves the emission and movement of energy. Some forms, such as visible light and radio waves, consist of oscillating electric and magnetic fields. Other forms, such as alpha and beta particles, consist of tiny bits of matter. Radiation that carries enough energy to remove tightly bound electrons from atoms is known as ionising radiation. Lower energy forms, like visible light or microwaves, are called non ionising radiation. Both types occur naturally and can also be produced by human activities.

Natural sources of radiation
Much of the radiation we encounter comes from natural sources. Cosmic rays from outer space strike the upper atmosphere and generate showers of particles that reach the ground. Rocks containing uranium, thorium or radium slowly emit radiation; in some areas the gas radon seeps from the soil into homes and contributes to indoor exposure. Even our own bodies contain trace amounts of radioactive potassium. Overall, background radiation levels vary by location but remain low enough that they pose little risk to health for most people.

Artificial sources of radiation
Human activity has introduced additional sources of radiation. Medical imaging techniques such as X ray and computed tomography rely on ionising radiation to produce detailed pictures of internal structures. Radiotherapy uses focused beams of radiation to destroy cancer cells. Nuclear power plants generate electricity through controlled nuclear reactions, and research laboratories and industrial facilities may handle radioactive materials for a range of applications. Everyday devices like television sets, microwave ovens and mobile phones use non ionising radiation to transmit information and cook food without producing ionisation.

How radiation interacts with matter
When radiation passes through material, it may be absorbed, scattered or transmitted. In the case of ionising radiation, absorption can strip electrons from atoms and molecules, creating charged particles known as ions. This process can damage biological molecules such as DNA, potentially leading to cell death or mutations. Non ionising radiation generally transfers energy in a gentler way, for example by causing atoms to vibrate and produce heat, as happens in a microwave oven.

Health effects of radiation exposure
The impact of radiation on health depends on the type, energy and duration of exposure. High doses of ionising radiation over a short period can cause radiation sickness, with symptoms that include nausea, vomiting and fatigue. Very high doses may lead to severe injury or death. Lower doses spread over many years carry an increased risk of developing cancer, although individual risk remains small compared with other everyday hazards. Non ionising radiation does not cause ionisation but can still produce biological effects such as skin warming or eye damage in the case of ultraviolet light from the sun.

Signs and symptoms of acute exposure
In the event of a large, acute exposure to ionising radiation, early warning signs include redness of the skin, a sensation similar to sunburn, followed by nausea or vomiting within hours. As exposure increases, hair loss, a drop in blood cell counts and infection risk may follow. Such severe exposures are rare outside specialised settings, but knowing the signs can help emergency responders identify and treat individuals who have received unintentional or occupational overexposure.

Benefits and uses of radiation
Radiation has many beneficial uses when applied safely. In medicine, X rays and CT scans save lives by revealing fractures, tumours and internal bleeding. Radiotherapy aims radiation precisely at malignant cells, shrinking tumours while sparing healthy tissue as much as possible. In industry, radiation gauges measure material thickness and composition, while nuclear power plants supply large amounts of low carbon electricity. Security scanners at airports use low doses of X rays to detect concealed items, and food irradiation uses controlled gamma radiation to eliminate bacteria and extend shelf life.

Measuring radiation
Radiation exposure is quantified in units designed to reflect biological impact. The gray measures the amount of energy deposited in a kilogram of tissue, while the sievert takes into account the type of radiation and its effect on different organs. A chest X ray may deliver around 0.02 millisieverts, whereas a CT scan of the abdomen can deliver two to ten millisieverts. Natural background exposure in the UK averages about 2.7 millisieverts per year. These figures help doctors, engineers and regulators assess risks and set safety limits.

Protection and safety
Protecting people from harmful radiation relies on three key measures: time, distance and shielding. Reducing the time spent near a source lowers the dose received. Increasing distance from a source reduces exposure according to the inverse square law, meaning exposure falls rapidly as you move away. Shielding with dense materials such as lead or concrete blocks the passage of many forms of ionising radiation. In occupational and medical settings, strict guidelines ensure that equipment, work practices and protective clothing keep doses as low as reasonably achievable.

Everyday precautions
Most people need only minimal precautions in daily life. Sun protection creams, clothing and sunglasses guard against ultraviolet light. When travelling to areas with high natural radiation levels, simple measures such as ventilating living spaces can reduce radon build up. If you live or work near industrial or medical radiation sources, following safety advice from authorities ensures that any additional risk remains negligible. Routine inspections and safety checks at clinics, laboratories and power plants maintain public confidence and protect workers.

When to seek help
If you believe you have been exposed to a large dose of ionising radiation, for example in an accident at work or in a radiology department, seek immediate medical attention. Early treatment of acute radiation sickness can improve outcomes. Similarly, if you experience unexplained skin redness or irritation after an occupational incident, your GP or occupational health service can arrange appropriate tests and monitoring. For concerns about living in a radon‑affected area, contact your local environmental health department for guidance on testing and remediation.

Common myths and misconceptions
A common misconception is that all radiation is lethal. In reality, everyday doses from natural and artificial sources are typically low and well within safety limits. Another myth is that radiation remains hazardous forever. While some radioactive materials have very long half‑lives, many medical isotopes decay to safe levels within hours or days. People also worry that mobile phones cause cancer through radio waves, but extensive studies have found no convincing link. Understanding the nature of different types of radiation and their energy levels helps dispel unfounded fears.

Emotional and mental health impact
Hearing the word radiation can provoke anxiety, especially after nuclear accidents or media reports of rising medical radiation use. Worry about invisible hazards may lead to sleepless nights or reluctance to undergo medically necessary scans. Sharing concerns with your doctor, a radiation safety officer or a counsellor can provide reassurance based on facts. Learning how doses compare with everyday exposures and how safety measures work helps restore confidence and reduces stress associated with perceived risks.

Summary
Radiation encompasses a wide range of energy forms, from harmless visible light to high energy particles capable of altering molecules. It plays an indispensable role in medicine, industry and power generation, yet carries potential risks if misused or encountered in large doses. By understanding the sources, effects, measurement and protection methods, you can appreciate the benefits of radiation and take sensible steps to avoid harm. Whether you face a medical scan, enjoy the warmth of the sun or work in a specialised setting, knowledge and prudent precautions ensure that radiation remains a tool for progress rather than a cause for undue alarm.