19 Nov 2015

The good and the bad of sunshine

From Our Changing World, 9:06 pm on 19 November 2015

Exposure during childhood is very important and it can be quite a large percentage of your total lifetime exposure. Reducing excessive exposure is one way we can reduce the burden of melanoma in this country.
Martin Allen, University of Canterbury

Sun light defines how we perceive our world. The visible spectrum of wavelengths emitted by the sun allows us to see, the infrared radiation provides life-giving warmth, and the ultra-violet radiation is essential for the production of Vitamin D, which in turn is important for bone health.

But too much exposure to UV radiation, which accounts for 9 per cent of the sun’s spectrum, burns our skin, damages collagen and DNA in skin cells, and is responsible for New Zealand’s high rates of melanoma.

Martin Allen, a material scientist at the University of Canterbury, has developed wearable sensors to monitor people's exposure to ultra-violet radiation.

Martin Allen, a material scientist at the University of Canterbury, has developed wearable sensors to monitor people's exposure to ultra-violet radiation. Photo: Supplied

The same high-energy wavelengths are both essential and damaging for health, says Martin Allen, a material scientist at the University of Canterbury, who has developed wearable electronic UV sensors to measure people’s exposure to UV and to work out how much is good and how much is bad.

Historically, UV exposure was measured with chemical badges, but the latest technology includes an electronic detector, linked to a micro-processor, which delivers a continuous measurement of how much UV is taken up by skin.

The size of a large button, the sensors can be pinned to a shirt, worn like a watch on a wrist band or attached to helmets or hard hats to monitor UV exposure of people who spend most of their day outdoors.

Martin Allen says he is particularly interested in monitoring UV exposure in children.  

"Exposure during childhood is very important and it can be quite a large percentage of your total lifetime exposure. Reducing excessive exposure is one way we can reduce the burden of melanoma in this country.”

Working with expat Kiwi researcher Myles Cockburn at the University of California, he has already introduced a sun-smart educational programme in schools in Los Angeles, with promising results.

Students were equipped with UV detectors which display their exposure levels in real time, and they set up their own dosimetry laboratory where they mapped out UV levels throughout their school grounds and set up experiments to test the protection levels of sunscreens, shaded areas and hats.

He says a similar programme is already underway at a school in Christchurch, mostly initiated by a student whose family has a history of melanoma, but he would like to see it rolled out in schools across New Zealand.

The whole idea is that if you get kids to learn things for themselves, with some guidance, but you actually give them the tools to learn for themselves, this leads to more lasting behavioural changes. And this is what they found. They found that sun safe behaviour improves when children do these kinds of experiments.

As part of his Rutherford Discovery Fellowship, he is also working on new materials that can pick up individual wavelengths in the sun’s UV spectrum to work out which of them are responsible for the skin damage and which are necessary for the Vitamin D production.

Martin Allen is one of the speakers in the Royal Society of New Zealand’s Luminaries lecture series which marks the International Year of Light. If you’re in Nelson on Monday, November 23, you can catch his lecture live at 7.30 at the Masonic Hall, or you can watch it on a live-stream.

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