ozone hole

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A large area of the ozone layer over Antarctica that annually becomes depleted of ozone by the action of chlorofluorocarbons and other pollutants.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A region of the stratosphere over Antarctica (and a smaller one over the Arctic) that is depleted of ozone in the local spring.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun an area of the ozone layer (near the poles) that is seasonally depleted of ozone