Uses for UV
There are a variety of ways we put ultraviolet (UV) radiation to good use.
Washing in the Sun
Drying washing in the Sun helps to protect us from infection because some of the bacteria present in the washing are inactivated by exposure to UVB.
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.
Sunbed research
Dr Richard McKenzie, Senior Research Scientist at NIWA, Lauder, has recently started to examine the spectrum of UV emitted by sunbed lamps. Here, he reports on an early result.
Acknowledgements:
Emperor Aquatics & UV Comparisons
Video thumbnail courtesy of Dmitry G, CC BY-SA 3.0
Researching UV and vitamin D links
Dr Richard McKenzie, Senior Research Scientist at NIWA, Lauder, talks about the relationship between exposure to UV radiation and the body’s production of vitamin D.
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.
Zapping bugs
Sanjay Kumarasingham (Watercare Services Ltd) talks about how microorganisms and viruses are zapped by UV radiation with a wavelength of 254 nm.
The best conditions to disinfect wastewater
Sanjay Kumarasingham (Watercare Services Ltd) talks about the ideal conditions for disinfecting wastewater effluent.
Acknowledgements:
UV Comparisons/Emperor Aquatics
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.
There is increasing interest in the uses of UVB and UVC to inactivate bacteria and viruses due to the rise of antimicrobial resistance. Practical applications range from treating drinking water to dentistry.
Astronomy
An ultraviolet image of the Sun
A false-colour image of the Sun's corona as seen in deep ultraviolet light at 17.1nm by the Extreme ultraviolet Imaging Telescope (EIT) aboard the SOHO spacecraft.
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”.
