Air Pollution:

EPA's Ambient Air Policy Results in Additional Pollution

RCED-89-144: Published: Jul 26, 1989. Publicly Released: Aug 17, 1989.


Richard L. Hembra
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Pursuant to a congressional request, GAO examined the Environmental Protection Agency's (EPA) use of pollution concentration estimates obtained from air quality dispersion models in carrying out its responsibilities under the Clean Air Act, focusing on whether EPA policies: (1) on ambient air quality resulted in approval of increased emissions; and (2) ensured the consistent use of air quality models in regulatory decisions.

GAO found that: (1) the EPA policy that defined ambient air as that portion of the atmosphere, external to buildings, which had public access, resulted in higher emissions limits than otherwise permitted; (2) EPA did not consider any air above company-controlled property as ambient air and exempted it from Clean Air Act requirements for air quality standards; (3) EPA stretched some policy decisions to allow some sources to increase emissions by acquiring additional land and restricting public access to it; and (4) there were four instances of noncompliance with EPA-recommended modelling policies and procedures, since EPA guidelines pertaining to model calibration were not sufficiently detailed to promote consistent understanding among model personnel.

Status Legend:

More Info
  • Review Pending-GAO has not yet assessed implementation status.
  • Open-Actions to satisfy the intent of the recommendation have not been taken or are being planned, or actions that partially satisfy the intent of the recommendation have been taken.
  • Closed-implemented-Actions that satisfy the intent of the recommendation have been taken.
  • Closed-not implemented-While the intent of the recommendation has not been satisfied, time or circumstances have rendered the recommendation invalid.
    • Review Pending
    • Open
    • Closed - implemented
    • Closed - not implemented

    Recommendations for Executive Action

    Recommendation: In light of the: (1) significant environmental consequences of the EPA policy which allowed increased emissions; and (2) feasibility of an alternative interpretation of ambient air boundaries which restricts the size of nonambient air, the Administrator, EPA, should initiate a formal rulemaking process to redefine ambient air in a manner that is more protective of the environment.

    Agency Affected: Environmental Protection Agency

    Status: Closed - Implemented

    Comments: EPA disagrees with the recommendation and does not believe its definition of ambient air needs to be reevaluated to offer greater protection to the environment. Should land acquisition result in an adverse impact on air quality in the future, EPA will reevaluate the need for additional restrictions.

    Recommendation: The Administrator, EPA, should review, and where necessary, revise the modelling guidelines to more clearly and precisely identify and prohibit unacceptable practices such as model calibration.

    Agency Affected: Environmental Protection Agency

    Status: Closed - Implemented

    Comments: EPA has developed a change to its guidelines on Air Quality Models that deal with the model calibration issue.

    Recommendation: The Administrator, EPA, should consider the need for a review of modelling performed by EPA regions and state and local air pollution control agencies to determine whether they are uniformly and consistently applying the modelling policies and procedures. If such a review detects inconsistent application of the modelling policies and procedures, then the Administrator should initiate corrective actions as deemed appropriate.

    Agency Affected: Environmental Protection Agency

    Status: Closed - Implemented

    Comments: EPA did not agree to review the modelling performed by its regions. However, it agreed to reemphasize the importance of its modelling program and promote the use of consistent modelling procedures.

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