A thin layer of Earth’s atmosphere shields the planet from some of the sun’s most harmful rays. It’s called the ozone layer. This band of gas protects us from ultraviolet (UV) rays. Too much exposure to UV rays can cause sunburn and skin cancer.

“The ozone layer is Earth’s natural sunscreen,” explains Steve Montzka. He is a scientist at the National Oceanic and Atmospheric Administration.

Scientists discovered a huge hole in the ozone layer above Antarctica in 1985. They determined the hole was caused by humanmade chemicals that were used in refrigerators and air conditioners, as well as spray cans.

In 1987, governments around the world agreed to phase out these chemicals. This change has had a positive effect. A recent report from the United Nations states that the ozone layer is slowly healing. Experts predict that it could be fully recovered within the next 45 years. This news makes Montzka hopeful.

“Human behavior caused the problem,” he says. “A human response found a way to work toward a solution.”