A global treaty curbing chemicals that destroy the ozone layer could prevent 443 million cases of skin cancer and 63 million incidents of vision damage that might have required cataract surgery by the end of this century, according to a new study.

“We peeled away from disaster,” explained Julia Lee-Taylor, an associate scientist at the National Center for Atmospheric Research who co-authored the paper on the Montreal Protocol.

The work is dedicated to Mario Molina, a Mexican chemist who shared a Nobel prize for his research beginning in 1974 predicting that chemicals commonly used for refrigerants and as propellants for aerosol cans were drifting into the stratosphere, where they emitted chlorine.

Molina warned that the chlorine was attacking the ozone layer, which helps shield the Earth from harmful ultraviolet radiation from the sun. His findings were greeted with skepticism at first, but in 1985, three British scientists discovered a huge “hole” in the ozone layer over Antarctica.

The resulting shock generated global support for the Montreal Protocol. It was the first step toward protecting the ozone layer, but it did not require a quick and complete phaseout of ozone-depleting chemicals.

The study released yesterday found that more than half of the treaty’s health benefits can be traced to six subsequent amendments that broadened its reach to cover more chemicals — including some being suggested as replacements — and sped up the timetables for removal.

“What is eye-popping is what would have happened by the end of this century if not for the Montreal Protocol,” noted Lee-Taylor, who said the treaty and its amendments have contributed “broad global benefits.”

Apart from health benefits, they include environmental benefits for crops, terrestrial wildlife and oceans.

The authors of the new study, which include scientists from NCAR and EPA, constructed a model projecting U.S. benefits based on health data and population projections in the future.

The model shows that the worst health effects from ozone-depleting emissions would be on Americans born between 1950 and 2000. They include skin aging and various types of skin cancer including melanoma, which causes over 7,100 deaths annually in the United States.

Overexposure to ultraviolet solar radiation can also reduce immunological defenses, including those that help people recover from COVID-19.

But the accelerated reduction of chemical emissions, including those of hydrofluorocarbons and chlorofluorocarbons, halons and other ozone destroyers, is expected to reduce UV radiation to 1980 levels by 2040.

That will also help reduce global warming because some of the chemicals, including those used for refrigerants, are regarded as super-warmers with more than 1,000 times the potency of CO2.

While some countries, particularly the United States, continue to have difficulties uniting around policies to slow climate change, the complex ozone treaty has been doing the job internationally.

Kofi Annan, a former secretary-general of the United Nations, appears to have been right when he suggested that the Montreal Protocol has been “perhaps the single most successful international agreement.”

Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2021. E&E News provides essential news for energy and environment professionals.