Chemicals used to make decaf coffee are contributing to ozone damage

Chemicals used to decaffeinate coffee, make paint strippers, melt plastics, and purify antibiotics contribute to the depletion of the ozone layer in the tropics.

The ozone layer has been recovering since the 1987 Montreal Protocol, when countries agreed to phase out the use of chlorofluorocarbons (CFCs) and other harmful aerosols. However, a part of it, the tropical lower stratosphere, has shown signs of depletion in recent years.

The researchers blame climate change for the discrepancy, as atmospheric warming accelerates the flow of warm air from the tropics to the poles, thinning the tropical ozone layer.

But research by Julián Villamayor and colleagues at the Institute of Physical Chemistry in Madrid, Spain, suggests that contamination from short-lived chemicals is also to blame.

Very short-lived substances (VSLS) are ozone-depleting chemicals that typically remain in the atmosphere for only six months. Some substances, such as bromine, occur naturally, while others, such as dichloromethane, are produced industrially. They are used in everything from caffeine extraction from coffee to aerosol spray propellants. Despite being known to attack the ozone layer, its use is not regulated by the Montreal Protocol.

These substances are having a negative impact on the ozone layer in the tropical lower stratosphere, Vimayor said. “They have such short lifespans that they don’t reach the stratosphere or the upper polar regions,” he says. “But very strong tropical convection forces it to enter the stratosphere and react in the lowest layers of the stratosphere.”

Villamayor and his colleagues used sophisticated climate models to simulate the impacts of all naturally occurring and man-made VSLS emissions on the ozone layer, and their damage to the layer in the tropics in the past. found that it may explain up to a quarter of the 20 years. The rest of the responsibility lies with climate change.

In the future, uncontrolled use of artificial VSLS could increase ozone depletion in the tropical stratosphere by 30 percent by the end of the century, Villamayor said.

This could severely affect millions of people living in the tropics, one of the world’s most populous regions, resulting in increased skin cancer incidence and reduced crop yields. , can lead to disruption of the marine food chain.

Villamayor said countries should consider amending the Montreal Protocol to limit the use of VSLS.

Neil Harris of Cranfield University, UK, said the study was robust and agreed that the use of VSLS should face tighter controls. “Definitely we need to work to reduce emissions of these compounds,” he says.