The chemical dichloromethane had been left out of the 1987 Montreal protocol, which banned the worst of the ozone-depleting chemicals, in part because it breaks down so quickly. But recent observations published in Nature Communications show its atmospheric concentration is now increasing at a rapid clip.

Concentrations of a paint-stripping chemical are building in the atmosphere and scientists believe it threatens to significantly delay repair of the damaged ozone layer, which shields the earth from high levels of harmful ultraviolet radiation.

The level of the chemical rose by 8 percent a year between 2004 and 2014, and using sophisticated computer models researchers found that if levels continue to grow, the recovery of the ozone layer would be delayed by 30 years, until about 2090. Little is known about where, exactly, the dichloromethane — which is used as an industrial solvent, an aerosol spray propellant, and a blowing agent for polyurethane foams — is leaking from or why emissions have risen so rapidly, reports the Guardian.



“Whatever the source of this gas, we must act now to stop its release to the atmosphere in order to prevent undoing over 30 years of exemplary science and policy work which has undoubtedly saved many lives,” said Grant Allen, an atmospheric physicist at the University of Manchester who was not involved in the study.