What is Radiation? - Ab.ust.hk

Ultraviolet Radiation (UV)
The bands:
- UV-A: 400 – 315 nm (near UV)
- UV-B: 280 – 315 nm (far UV)
- UV-C: 100 – 280 nm (vacuum UV)
• The wavelength of 260 – 280 nm UV light is
generally considered the most hazardous to the
eyes.
Biological Effect to UV
• Effects on skin
- Acute effects (急性效應)
o Erythema (reddening skin) (紅斑) is a photochemical
response of the skin. (UV-B and UV-C).
- Chronic effects (慢性效應)
o Accelerate skin aging (UV-B)
o Develop skin cancer (UV-B and UV-A) strongly
correlated with latitude, altitude and cloud cover.
o Vitamin D synthesis.
UV Radiation Hazard
• High intensity of UV can generate ozone in air.
(usually at UV-B and UV-C).
• Ozone is a irritation gas.
• Adverse effect to lung function when receive
large dose of ozone gas.
• Photo-chemical smog formation to cause air
pollution in urban city.
Smog formation = NO x + Ozone + hydrocarbon
Solar UV
• The solar UV is greatly attenuated by the
earth’s ozone layer(臭氧層), limiting
terrestrial UV to wavelength up to 290 nm.
• Component of solar UV reaches earth’s
surface:
• 5 - 10% of UV-C;
• 50 - 60% of UV-B;
• 80 – 90% of UV-A.
Biological Effects to UV
• Effect on the eyes
- Acute effects
o Photokeratitis (光化性角膜炎)(snowblindness)
commonly referred to as welder’s flash / arc-eye.
o Painful last from 6 to 24 hours, disappear within 48
hours.
- Chronic effects
o Protein deposit or growth in the cornea.
o Cataracts (白內障)
o Conjunctiva (結膜炎)
Protective Measures
• Depending upon whether the UV radiation
exposure occurs indoors or outdoors.
• Outdoor: the use of hats, eye protectors, facial
shields and clothing are practical.
• Indoor: engineering control measures are
preferable.