Experts are warning Kiwis to take extra care when out in the sun this summer due to rising levels of ultraviolet (UV) radiation after a recent depletion in the ozone layer.
According to the National Institute of Water and Atmospheric Research (Niwa), UV index levels have risen by up to 10 per cent around Auckland over the last month compared to last year.
The higher the UV index, the stronger the sun's UV rays and the faster a person may burn, Niwa explained. A UV index level of three or more is enough to cause skin damage.
It has already reached UV level eight in New Zealand this week. For comparison, UV eight is rare in the UK, even in the height of summer.
Over the Labor Day weekend, UV Index levels are expected to reach six to seven in the south of the country, seven to eight in the central parts, and 8 to 9 in the north.
Niwa meteorologist Dr Richard Turner said the high levels of radiation are caused by our ozone layer depleting over the last few months.
"Our atmosphere shields us from a lot of the sun's radiation because of the thin ozone layer in our stratosphere, which absorbs most of the UV," Turner said.
"However, values taken at our atmospheric research station in Lauder show that ozone levels are at the lower end of what we'd expect at this time of the year."
Although the ozone layer naturally degrades and regenerates, it has gotten thinner over time. This is especially noticeable over Antarctica, where a sizable hole emerges in the spring, having an impact on New Zealand during the summer, Turner said.
The most frequent culprits are synthetic chemicals like CFCs, which were phased out in the 1990s but continue to circulate in our environment today.
Volcanic eruptions are another factor in ozone depletion. This is causing some experts to speculate that what we are currently seeing may be related to the underwater Tongan volcano's eruption in January, which resulted in the largest explosion in recent history.
Luckily, any effect from the Tongan volcano on the ozone is reversible, as the water will be removed from the stratosphere in a few years.
Until then, this is of particular worry in New Zealand because our ozone layer is already among the weakest in the world, according to Hazel Potterton, the SunSmart national adviser from the Cancer Society of New Zealand.
"New Zealand often ranks highest in the world for skin cancer rates. Even on cloudy days, you can burn within minutes, and people are often caught out at this time of year," Potterton said.
"The good news is, you can help protect yourself by being SunSmart and remembering to slip, slop, slap, and wrap," she said.
This means slipping on clothes to cover as much skin as possible; slipping into shade, especially during the middle of the day; slopping on sunscreen of at least SPF 30 every two hours; slapping on a wide-brimmed hat; and wrapping on close-fitting, sun-protective sunglasses.