Scientists Report a Hole in the Ozone Layer

In May 1985, researchers published atmospheric measurements showing that concentrations of stratospheric ozone over Antarctica were dropping sharply each southern spring. Measurements at the British Antarctic Survey's Halley station showed that by 1984 the springtime ozone layer overhead was only about two-thirds as thick as it had been in earlier decades. Instruments measuring atmospheric thickness revealed that this seasonal decline, soon known as the ozone hole, reduced ozone levels over the continent to a fraction of their historical baselines. An independent team quickly confirmed the findings, and satellite data showed that the depletion extended over a vast region of the Antarctic sky.

Stratospheric ozone shields the surface of the Earth by absorbing biological wavelengths of ultraviolet radiation, specifically UVB light. Ozone molecules, composed of three oxygen atoms, form continuously when ultraviolet photons split molecular oxygen, prompting the liberated atoms to combine with existing pairs. Because ozone absorbs most incoming UVB radiation, any broad decrease in its abundance permits greater amounts of high-energy light to reach the ground. The resulting exposure was projected to elevate rates of sunburn, cortical cataracts, and non-melanoma skin cancers, while disrupting microalgae and terrestrial plant life.