This year's ozone hole over Antarctica was the fifth biggest on record, reaching a maximum area of 10.5 million square miles in September, NASA says.
That's considered "moderately large," NASA atmospheric scientist Paul Newman said in a statement.
NASA has tracked the size of the hole for 30 years. Last year, it was 9.7 million square miles, about the size of North America.
The hole is an area of depletion in the stratospheric ozone layer, which blocks harmful ultraviolet rays from space. Created by human-produced gases, the ozone hole generally forms in August and grows to its maximum size in September or October before breaking up.