A bill to amend the Clean Air Act.

Amends the Clean Air Act to require the Administrator of the Environmental Protection Agency to include in the Agency's study of the cumulative effect of substances on the stratosphere, particularly, the ozone, the effects of other trace gases. Grants priority in such study to increasing and improving measurements of ozone and other chemical species in the atmosphere that would indicate potential trends in actual ozone.

Grants priority in other studies and research to a quantitative analysis of any effects of statospheric changes on human health, crops, and the ecosystem.

Directs the Administrator to contract triennially with the National Academy of Sciences to study and evaluate changes in the ozone and their effects. Requires the Academy to report triennially to the Administrator and to the Congress on the concentration of ozone in the stratosphere and its causes and implications.

Requires that other Federal agency studies concerned with the stratosphere be continued, with an emphasis on studying and monitoring any changes in the ozone and their effects.

Directs the President to enter into international agreements to reach consensus on the causes of and responses to the ozone problem. Requires the President to report annually to the Congress on the status of such efforts.

Directs the Administrator to regulate chlorofluorocarbons only if they are determined to be causing a dangerous depletion in the ozone and such regulation is feasible and cost-effective.