Know your Risk

An app a day keeps the doc away

New Zealand and Australia are arch rivals on the sports field. But the two countries share one unenviable record. They have by far the highest rates of skin cancer in the world. The at-risk group have skin types better suited to northern Europe where the peak UV is only half that in New Zealand. The UV is even more intense in Australia, but the warmer temperatures there encourage more shade-seeking behavior than in New Zealand with its cooler climate. In New Zealand, your chance of dying from skin cancer is about the same as your chance of dying in a road accident (about 300 deaths per year for a population of 4.5 million). Both of those causes of death are preventable.

Thanks to the success of the Montreal Protocol on Protection of the Ozone Layer that I discussed last week, the risk from UV damage is no longer increasing. But the problem of skin damage caused by UV exposure will remain for the foreseeable future.

You can reduce your risk of skin cancer by cutting back on your exposure to UV. But how much is safe? It varies hugely with sun elevation angle, cloud cover and ozone amount. But you can’t see differences in UV, and it’s not just proportional to air temperature.

To answer the question of how much is safe, I persuaded my old friend Jerry Burke to put his computer programming skills to use and create a smartphone app that provides the missing UV information, along with appropriate behavioural messages that are matched to your skin type.

The app is called GlobalUV. As the name implies, it works anywhere in the world. The calculation method is described here. The app even tells you your location and altitude (it needs to know where you are to calculate the UV), and shows a flag to remind you what country you’re in. If you only want to know much ozone there is overhead, it also tells you that. It shows the current UV, how it compares with other locations, and how the peak daily UV compares with other locations.

As well as giving the current UV at your location (or any other selected location on the planet), the app also shows how it will vary over the day. It can therefore be used to plan your day to optimize your UV exposure. You’ll probably end up wanting to play that round of golf in the early morning, rather than near the midday period.

If you are lucky enough to live in New Zealand, there’s another app, called uv2Day, which has more detailed cloud forecasts. With the southern hemisphere summer just around the corner, it’s a good time to load it and give it a try. We’ll soon be releasing a new better app for the New Zealand region – which will be advertised through an update to uv2Day. Set your phone for automatic updates of the app to make sure you don’t miss the new one …..

The apps report the UV in terms of the UV Index (UVI), which is a measure of skin-damaging UV. They are freely available for iPhone and Android.