Ozone layer's revival saves thousands from skin cancer – study

  • Breaking
  • 26/05/2015

New Zealand and Australia have the highest skin cancer mortality rates in the world, but it could have been much worse had the use of chlorofluorocarbons not been phased out in the 1990s.

According to a new study, the hole in the ozone layer above Antarctica would now be 40 percent larger than it was in 1989, when the Montreal Protocol came into force.

Surface levels of UV radiation would also be between 8 and 12 percent higher, computer modelling carried about by the University of Leeds and the National Institute of Water and Atmospheric Research (NIWA) suggests.

Just a 5 percent increase in exposure to UV radiation would lead to between 15 percent and 18 percent more cases of the most common forms of skin cancer.

"Just over two decades since it was ratified, the Montreal Protocol has already had major beneficial impacts, including avoiding an Arctic ozone hole," the study notes.

The international agreement, signed in 1987, was the first universally ratified treaty in the history of the United Nations. Former Secretary-General Kofi Annan called it the "perhaps the single most successful international agreement to date".

Exact skin cancer rates in New Zealand are hard to quantify because unless it's melanoma, doctors aren't required report it to the Ministry of Health. The Government-funded Science Learning Hub says around 45,000 cases of basal cell or squamous cell carcinomas are confirmed in laboratory tests every year, and estimates there are another 25,000 annual cases treated immediately without lab testing.

More than 2000 Kiwis are diagnosed with melanoma every year.

In the northern hemisphere, the annual ebb and flow of the Arctic ozone hole – though smaller than that in the Antarctic – would have led to an increase in UV radiation in the UK of around 14 percent, had CFCs not been phased out. The particularly cold northern winter of 2011 would have seen the Arctic hole depleted to "unprecedented" levels.

"While health effects are hard to quantify, the continued reduction in atmospheric emissions of chlorine and bromine should eventually translate into an increase in stratospheric ozone, reducing the incidence of skin cancer and preserving the temperature structure of the atmosphere, with important long-term consequences for circulation and climate."

Chlorofluorocarbons, also known as CFCs, were widely used in refrigeration, aerosol cans and solvents. They've since been largely replaced with other compounds, some of which come with their own problems – such as hydrofluorocarbons, which although harmless to the ozone layer, are a greenhouse gas.

The study is published today in journal Nature Communications.

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