The hole in the ozone layer over the Antarctic could be the smallest seen in three decades, scientists believe.

The ozone layer in the atmosphere protects life on Earth from harmful ultraviolet radiation from the sun.

In the late 20th century, human emissions of chemical substances called halocarbons adversely affected the amount of ozone molecules in the stratosphere, resulting in a dramatic annual ozone hole over the Antarctic region.

According to the European Union’s Copernicus Atmosphere Monitoring Service (CAMS), this year the hole is well under half the size usually seen in mid-September.

"Right now I think we should view this as an interesting anomaly. We need to find out more about what caused it,” Richard Engelen, deputy head at CAMS told the BBC.

"It's not really related to the Montreal Protocol where we've tried to reduce chlorine and bromine in the atmosphere because they're still there. It's much more related to a dynamical event.

“People will obviously ask questions related to climate change, but we simply can't answer that at this point."

The Montreal Protocol, which came into force in 1987, has curbed the amount of halocarbons in the atmosphere, resulting in the slow recovery of the ozone layer, CAMS said.

CAMS combines measurements from satellite instruments and sensors with numerical models to provide information about the state of the ozone layer.

The hole in the ozone now covers an area of three million square kilometres, down from 12.3 million square kilometres in September 2018, reports the BBC.