This is because, in the absence of a protective ozone layer, the land was bathed in lethal levels of UV radiation.

这是因为，在没有防护臭氧层时，土地沐浴了在紫外辐射的致死的水平。

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Ozone forms a protective layer between 12 and 30 miles above the Earth's surface.

臭氧在距地球表面12至30英里的地方形成一个保护层。

《柯林斯英汉双解大词典》

Scientists have disclosed further details about a giant hole in the protective Ozone layer above the arctic. It matched the size of those found regularly over Antarctic .

科学家透露更多关于北极具保护性的臭氧空洞问题，面积相当于南极的空洞。

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Ozone is a protective atmospheric layer found at an altitude of about 25 kilometers (15.5 miles).

CNN: Ozone hole grows in 2008