A large hole in the ozone layer, estimated to be seven times the size of the Antarctic hole, settled over the tropical region of the planet in the 1980s. Since then, the problem persists in the lower stratosphere, as reported study published on Tuesday (5) in the journal AIP Advances.

Compared to the undisturbed atmosphere, the hole represents a region with ozone loss greater than 25%. This extent is comparable in depth to that of the hole that forms in Antarctica in the spring in September, although its area is larger.

"The tropics make up half the planet's surface and are home to about half of the world's population," Qing-Bin Lu, a scientist at the University of Waterloo in Canada who leads the study, said in a statement. "The existence of the tropical ozone hole can cause great global concern.

Lu observed the hole by raising unforeseen data in conventional photochemical models. The information followed another model, that of electronic reaction triggered by cosmic rays (CRE), in which cosmic rays from space reduce ozone in the atmosphere.

The analysis pointed out that an identical mechanism occurs both in the antarctic holes and in the tropics. About 80% of the normal amount of gas is depleted in the center of the tropical hole. In equatorial regions, its reduction already puts large populations at risk, with higher than expected ultraviolet (UV) radiation.

"Depletion of the ozone layer can lead to increased UV radiation at ground level, which can increase the risk of skin cancer and cataracts in humans, as well as weaken the immune system, decrease agricultural productivity and negatively affect aquatic organisms and sensitive ecosystems," explains the author of the research.

The study was based on studies by Lu and his colleagues about two decades ago. In the mid-1970s, other studies suggested that the ozone layer could be threatened by industrial chemicals, mainly chlorofluorocarbons (CFCs). In 1985, with the discovery of the hole in Antarctica, this theory was confirmed, resulting in the prohibition of such products.

Tropical and polar holes cool and regulate stratospheric temperatures and are a sign of climate change. In Lu's view, research can be crucial to better understand these changes. "This discovery requires more careful studies on the destruction of the ozone layer, uv radiation change, increased cancer risks, and other negative effects on health and ecosystems in tropical regions," he says.

Source: Um só Planeta