Low ozone events over Europe are of great interest

Ankie Piters, climate researcher

Levels of ozone in the atmosphere will fall to 60-70% of the seasonal average as the hole deepens, according to scientists at the climate research centre, KNMI, in The Netherlands.

But they say the mini ozone hole does not present a significant threat to health.

"At this time of the year at our latitudes, the Sun does not rise high enough above the horizon to deliver a significant amount of harmful ultra-violet light," says Ankie Piters at KNMI. "But low ozone events over Europe are still of great interest."

The ozone loss was detected by an instrument aboard the European Space Agency probe ERS-2. The device collects data in real time, allowing scientists to track the movement of the ozone hole from hour to hour.

Ultra-violet shield

The mini-hole over Europe seems to be appearing because of unusual air currents in the atmosphere.

The ozone loss is not thought to be linked to the breakdown of ozone by chemicals.

Measurements of the hole over Antarctica taken in 1986

Emissions of ozone-depleting gases have been blamed for the much larger hole over Antarctica.

The chemicals include chlorofluorocarbons and halons, now limited under the Montreal Protocol, and bromine compounds, some of which are new and not covered by the international agreement.

In September, the Antarctic ozone hole measured 26 million square kilometres (10 million square miles), almost as bad as the worst year recorded.

The ozone layer helps to shield the Earth's surface against harmful ultra-violet radiation from the Sun.