A United Nations weather and climate agency says ozone loss over the arctic reached record levels this spring because of ozone-depleting substances and weather.

The arctic region has suffered an ozone loss of about 40 percent from the beginning of the winter to late March, a release by the World Meteorological Organization said Tuesday.

The highest loss previously recorded was about 30 percent over the entire winter, the organization said

"The arctic stratosphere continues to be vulnerable to ozone destruction caused by ozone-depleting substances linked to human activities," organization Secretary-General Michel Jarraud said.

The record loss is despite the success of the Montreal Protocol cutting production and consumption of ozone-destroying chemicals such as chlorofluorocarbons and halons once present in refrigerators, spray cans and fire extinguishers.

"Without the Montreal Protocol, this year's ozone destruction would most likely have been worse," the meteorological group said. "The slow recovery of the ozone layer is due to the fact that ozone-depleting substances stay in the atmosphere for several decades."

The depletion of the ozone layer is also due to a very cold winter in the stratosphere, the organization said, noting that even though this arctic winter was warmer than average at ground level, it was colder in the stratosphere than for a normal arctic winter.

Significant arctic ozone loss is possible in the case of a cold and stable Arctic stratospheric winter, it said.