Story highlights Scientists credit the ozone layer's gradual healing to a chemical ban

Since 2000, ozone hole has decreased by about 1.5 million square miles

(CNN) The Antarctic ozone layer, which shields the Earth from harmful ultraviolet rays, shows encouraging signs that it's beginning to heal, according to research published in the journal Science.

Scientists credit the healing to an international policy set nearly three decades ago that cut the production of ozone-destroying chemicals. That agreement -- the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer -- called for the phase-out of substances including chlorofluorocarbons and halons, once present in refrigerators, aerosol cans and dry cleaning chemicals.

"The ozone layer is expected to recover in response, albeit very slowly," wrote the researchers in the study which was released Thursday.

"We can now be confident that the things we've done have put the planet on a path to heal," said Professor Susan Solomon of the Massachusetts Institute of Technology, who led the international team of researchers, in a statement . "We decided collectively, as a world, 'Let's get rid of these molecules'. We got rid of them, and now we're seeing the planet respond."

The ozone layer, a fragile shield of gas, protects animal and plant life on Earth from powerful UV rays. When the ozone layer is weakened, more UV rays can get through and affect humans, making them prone to skin cancer, cataracts and other diseases. There also may be consequences for plant life, including lower crop yields and disruptions in the ocean's food chain.

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