New assessments of ozone depletion

A National Academy of Sciences–National Research Council panel has doubled its earlier estimate of stratospheric ozone depletion by halocarbons, though a British government report says that our present understanding of ozone depletion is limited and makes such estimates of doubtful significance. The NRC panel on stratospheric chemistry and transport, headed by Harold Schiff of York University, Toronto, concluded that continued world‐wide use of halocarbons will result in ozone depletion that is calculated to reach 16.5%, half of which will occur in the next 30 years. A 1976 NRC report estimated the eventual ozone reduction at 7.5% (PHYSICS TODAY, November 1976, page 101).