Uses for UV

There are a variety of ways we put ultraviolet (UV) radiation to good use.

Our skin and UV

When we expose our skin to UVB, it stimulates the production of vitamin D, which our bodies need. Window glass absorbs UVB, so people need to go outside to gain the benefit. However, too much exposure to UVB can cause skin cancers, so the aim is to find the optimum amount of exposure. UV lamps are used in sun beds to give the users a sun tan, but this use of UV is controversial.

Sterilisation and disinfection

UVB also helps us when we hang washing outside to dry, as some of the bacteria present in the washing are inactivated by exposure to UVB. This helps to protect us from infection and is another reason to dry washing outside rather than in an energy-hungry dryer.

The ability of UV to inactivate bacteria and viruses is taken further by using artificially produced UVC to sterilise surfaces of things such as medical equipment. Auckland’s sewage treatment plant uses UVC to inactivate bacteria and viruses just before discharging the clear effluent into the Manukau Harbour.

Often UVC is called “germicidal UV” because it is able to directly disable the strands of DNA in bacteria and viruses and make them inert. Inactivated bacteria and viruses are as good as dead because they are not able to reproduce and multiply.

Astronomy

Very hot objects emit some amount of UV radiation. The hotter the object, the more UV is emitted. Observing and recording the UV from astronomical objects such as planets in our solar system, stars, nebulae and galaxies enables us to gain extra information such as the temperature and chemical composition of these objects. The only problem is that our Earth’s ozone layer absorbs much of the UV and so these observations need to be made outside the Earth’s atmosphere. On board the Hubble Space Telescope, the Faint Object Spectrograph (FOS) and the Goddard High Resolution Spectrograph (GHRS) are used to collect and analyse UV light from interesting targets.

The Solar and Heliospheric Observatory (SOHO) is a spacecraft that was launched in 1995 to study the Sun. It is a joint project of international cooperation between the European Space Agency (ESA) and NASA. Two of SOHO’s twelve instruments are used to record and analyse UV radiation from the Sun.

Fluorescence and lighting

A number of substances are able to absorb the energy in UV light and immediately convert it into visible light. This effect is called fluorescence. The ink in highlighter pens contains a fluorescent dye that enables the ink to reflect vividly in sunlight and to glow strongly in the dark when a UV lamp is shone on it.

Nature of science

Entrepreneurial scientists look to find commercial applications of science findings, knowledge and techniques.

We can use UV and fluorescence to make efficient lighting for offices, workshops and our own homes.

Curing

UV radiation used to be called “chemical rays” after it was first discovered in the early 19th century. This was because UV could make certain substances change chemically. This effect is put to use in a number of ways, one of which is to harden special glues quickly. This process is called “curing”.

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