In 1980 there was growing concern that the protective ozone layer over the Antarctic might be decreasing and thereby allowing so much harmful ultraviolet radiation to reach the Earth that polar marine life would be damaged. Some government officials dismissed these concerns, since statistics indicated that global atmospheric ozone levels remained constant. The relevance of the evidence cited by the government officials in support of their position would be most seriously undermined if it were true that ['quantities of atmospheric ozone shifted away from the polar caps, correspondingly increasing ozone levels in other regions', 'decreases in the amount of atmospheric ozone over the Antarctic ice cap tend to be seasonal rather than constant', 'decreases in the amount of atmospheric ozone were of little concern before 1980', "even where the amount of atmospheric ozone is normal, some ultraviolet light reaches the Earth's surface"]