Different types of electromagnetic radiation pose different biological risks depending on their frequency, energy and penetrating power.
Radiation hazards and safety
| Type | Hazard | Safety measures |
|---|---|---|
| Radio waves | Generally considered safe at normal levels | Exposure limits for high-power transmitters |
| Microwaves | Heating of body tissue (internal organs, eyes) | Metal casing in microwave ovens; exposure limits for phone masts |
| Infrared | Burns to skin | Protective clothing; tongs for hot objects |
| Visible light | Eye damage from intense sources (lasers, Sun) | Do not look directly at the Sun; laser safety goggles |
| Ultraviolet | Sunburn; skin cancer; eye damage (cataracts) | Sunscreen; protective clothing; UV-blocking sunglasses |
| X-rays | Cell damage; cancer from cumulative exposure | Lead shielding; minimal exposure time; film badges for workers |
| Gamma rays | Cell damage; cancer; radiation sickness at high doses | Lead/concrete shielding; remote handling; monitoring exposure |
Why higher frequency is more dangerous
Higher-frequency radiation (UV, X-rays, gamma) carries more energy per photon. This energy can ionise atoms in living cells, damaging DNA and causing mutations that may lead to cancer.
Lower-frequency radiation (radio, microwave, infrared) is non-ionising. It causes heating effects but does not directly damage DNA.
The ionisation boundary
Ultraviolet sits at the boundary between non-ionising and ionising radiation. UV-A (longer wavelength) is less harmful; UV-B and UV-C (shorter wavelength) are more dangerous.
Common errors and how to correct them
- Saying all EM radiation is dangerous. Radio waves and visible light at normal intensities are safe.
- Confusing ionising and non-ionising radiation.
How to apply this in an exam
Name the specific hazard for each type. State a practical safety measure. Explain why higher-frequency radiation is more dangerous (higher energy, ionising).
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