During the past year, the Environmental Protection Agency (EPA) has come under increasing pressure to rectify what some segments of industry, the public, and the Carter Administration see as the excessive compliance costs and overly intrusive character of certain environmental standards and requirements. Partly in response to those concerns and partly as a result of its own burgeoning interest in the use of economic incentives as a pollution control device, the Agency has recently begun to place more emphasis on flexibility and economic efficiency in its regulatory programs.One such change has been the Agency's embrace of the "bubble" concept in a widening variety of regulatory contexts.

The basic idea behind the "bubble" is to treat the various buildings and facilities which make up an industrial plant as a single source for regulatory purposes. In essence, emissions from all stacks or discharges from all outfalls of the complex are considered only in the aggregate. Offsetting increases and decreases in emissions or discharges from various plant components entail no additional regulatory consequences so long as the net effect is not to increase the aggregate amount. The concept is generally similar to EPA's policy of allowing new sources to be constructed in non-attainment areas if their emissions would be more than offset by reductions at existing sources,¹ except that under the bubble, emission trade-offs occur only within a single plant.