14.6 - Dangers of Electromagnetic Radiation

Why high-frequency EM radiation can harm the body

• Whether EM radiation is harmful depends on how much energy it transfers to living tissue.
• The higher the frequency, the more energy the radiation carries, and generally the more harmful it is.
• Low-frequency radiation (e.g. radio waves) passes straight through soft tissue without being absorbed.
• High-frequency radiation (e.g. ultraviolet, X-rays, gamma rays) transfers large amounts of energy and can cause severe damage.

Ultraviolet, X-rays and gamma rays are ionising

• These are types of ionising radiation: they carry enough energy to knock electrons off atoms, damaging living cells.
• Ultraviolet (UV) - Absorbed by the skin, where it damages surface cells. It can cause premature ageing of the skin, skin cancer, and eye damage including blindness.
• X-rays and gamma rays - Carry even more energy than UV. They pass through the skin and are absorbed by deeper tissues, damaging cells throughout the body and leading to mutations and cancer.

Lower-frequency hazards - Microwave and infrared

• Radiation doesn't have to be ionising to be harmful. Microwaves and infrared can damage the body by heating it.
• Microwaves - Have a similar frequency to the vibrations of many molecules, causing internal heating of body cells.
• Infrared (IR) - Absorbed by the surface of the skin, where high exposure causes skin burns.