How does ozone depletion allow more ultraviolet radiation to reach Earth’s surface?

The ozone layer acts as a protective shield in the stratosphere, effectively absorbing and blocking most harmful ultraviolet (UV) radiation—specifically UVB—from reaching Earth's surface.123

Ozone depletion occurs primarily when human-made chemicals, such as chlorofluorocarbons (CFCs) and other halocarbons, release chlorine and bromine into the atmosphere. These elements catalyze the destruction of ozone molecules, thinning the layer and creating regions of severely reduced coverage known as ozone holes.14

As the concentration of stratospheric ozone declines, the atmosphere's ability to screen out these rays is compromised. Consequently, higher levels of UVB radiation penetrate the atmosphere and reach the surface. This increased exposure poses significant risks to ecosystems and human health, as intense UV radiation can damage DNA, contribute to skin cancer, and harm marine life such as plankton and krill.134