opinion: STATE OF OHIO, Commonwealth of Massachusetts, Cleveland Electric Illuminating Company, Northern Ohio Lung Association, North American Coal Corporation and Nacco Mining Company, Petitioners, Commonwealth of Pennsylvania, State of New York, State of New Hampshire, Ohio Mining and Reclamation Association, and Youghiogheny & Ohio Coal Company, Intervenors, v. UNITED STATES ENVIRONMENTAL PROTECTION AGENCY, Anne M. Gorsuch, Administrator, Respondents.
  Nos. 80-3575, 80-3576, 80-3579, 80-3581, 80-3582 and 81-3525.
  United States Court of Appeals, Sixth Circuit.
  Argued Jan. 15, 1985.
  Decided Aug. 7, 1986.
  William J. Brown, Atty. Gen. of Ohio, Robert J. Styduhar, Asst. Atty. Gen., Environmental Law Section, Dale T. Vitale, Office of the Atty. Gen., Environmental Enforcement Section, Columbus, Ohio, A. Mark Segreti, Jr. (argued), Bieser, Greer & Landis, Dayton, Ohio, Michael L. Hardy (argued), Thompson, Hiñe & Flory, Cleveland, Ohio, for petitioners.
  Peter S. Everett, U.S. Dept, of Justice, Land and Natural Resources Div., Environmental Defense Section, Richard B. Ossias (argued), U.S.E.P.A., General Counsel, Air & Radiation Div. LE-132, Michael M. Wenig, Environmental Defense Section, Land and Natural Resources Div., Washington, D. C., Catherine L. Fox and Susan W. Schaffer, Office of Regional Counsel, U.S. E. P.A., Chicago, 111., Lydia Wegman, Office of General Counsel, U.S. E.P.A., Washington, D.C., for respondents.
  Michael McMahon, Benesch, Friedlander, Copian & Aranoff, Alan D. Wright, Donald H. Havser, Cleveland, Ohio, for Cleveland Elec. Illuminating Co.
  Ronald R. Janke, Jones, Day, Reavis & Pogue, Cleveland, Ohio, for North American Coal Co. and Nacco Min. Co.
  John W. Edwards, Smith & Schnacke, Columbus, Ohio, for Ohio Min. and Reclamation Ass’n.
  William W. Falsgraf, Baker & Hostetler, Cleveland, Ohio, for Youghiogheny & Ohio Coal Co.
  Janet McCabe, Asst. Atty. Gen., Environmental Protection Div., Dept, of the Atty. Gen., Boston, Mass., for State of Mass.
  Thomas Y. Au (argued), Asst. Atty. Gen., Dept, of Environmental Resources, Harrisburg, Pa., for Com. of Pa.
  George Dana Bisbee, Asst. Atty. Gen., Environmental Protection Div., Concord, N.H., for State of N.H.
  Francis X. Bellotti, Atty. Gen. of Mass., Stephen M. Leonard, Asst. Atty. Gen., Janet G. McCabe, Stephen M. Leonard, Lee Breckenridge, Environmental Protection Div., Public Protection Bureau, Dept, of the Atty. Gen., Boston, Mass., for Com. of Mass.
  Ronald R. Janke, Thomas R. Jackson, Jones, Day, Reavis & Pogue, Cleveland, Ohio, for North American Coal Co. and Nacco Min. Co.
  Robert Abrams, David R. Wooley, Atty. General’s Office, New York City Dept, of Law, Environmental Protection Bureau, Albany, N.Y., for State of N.Y.
  Before ENGEL, MERRITT and MILBURN, Circuit Judges.
  MERRITT, Circuit Judge.
  This opinion follows our earlier opinion in Ohio v. E.P.A., 784 F.2d 224 (6th Cir.1986). There we held that the EPA’s use of CRSTER, a computerized atmospheric model, was arbitrary and capricious in the absence of site-specific validation studies. We then ordered the parties to propose a program for validating the CRSTER model, and a set of interim emissions limits for use until the validation process has been completed. The parties have now responded, and the Court has before it and has read and considered (1) the Group III petition for rehearing and rehearing en banc, (2) EPA’s petition for rehearing, (3) each party’s response to those two petitions, and (4) each party’s response to the two questions presented for comment in the Court’s opinion and order of February 26,1986, 784 F.2d 224.
  As the full Court has not exercised its discretion to review this case en banc, the case is back before the panel. We hold as follows:
  First, the panel reaffirms its decision. On the present record the use of the CRSTER model without validation to forecast SO2 diffusion at the two plants adjacent to Lake Erie is arbitrary and capricious. Instead of simply deferring to EPA’s decisions regarding scientific and computer models, as EPA and the Group III petitioners urge, the legislative history of the 1977 Clean Air Act indicates that the Courts are to conduct a “searching review” of the basis of EPA modeling and test procedures like the one at issue here. See No. 294, 95th Cong. 1st Sess., 1977 U.S. Code Cong. & Ad.News 1077, 1397, 1402. See also H.Conf.Rep. No. 95-564,1977 U.S. Code Cong. & Ad.News 1502, 1559 (calling for “thorough, comprehensive review”). Our inquiry indicates that the specific meteorological and geographic problems present at these sites were not adequately resolved in using the CRSTER model without validation. Based on the CRSTER model, EPA has reversed its field and has allowed 400% more SO2 than its original order permitted — all without evaluation, validation, or empirical testing of the model at the site, a site where the parties agree that the lakeshore effects on the dispersion of SO2 are significant but as yet untested and unknown (at least on the basis of the present record). See Motor Vehicle Mfg. Assn. v. State Farm Mutual, 463 U.S. 29, 41-42, 103 S.Ct. 2856, 2865-66, 77 L.Ed.2d 443 (1983) (agency “changing of course by rescinding rule” requires closer judicial scrutiny). By no means does the Court insist that all models be validated at all sites. We find only that the accuracy of CRSTER at the site has not been sufficiently demonstrated to meet the arbitrary and capricious standard of review.
  Second, although the Court originally considered saving the time and expense of starting over at the agency level by ordering the parties to propose an appropriate evaluation procedure for the CRSTER model, both EPA and the Group I petitioners have requested that we remand the case to EPA for de novo resolution of the issue.
  Accordingly, the case will be remanded to EPA for further proceedings consistent with this opinion and our opinion of February 26, 1986. EPA will submit a proposed order of remand within 20 days from the date of filing of this opinion. The other parties will submit their comments and alternative proposals for an order of remand within 10 days following the date of filing of EPA’s proposed order of remand.
  It is so ordered.
instruction: What follows is an opinion from a United States Court of Appeals.
  Intervenors who participated as parties at the courts of appeals should be counted as either appellants or respondents when it can be determined whose position they supported. For example, if there were two plaintiffs who lost in district court, appealed, and were joined by four intervenors who also asked the court of appeals to reverse the district court, the number of appellants should be coded as six.
  In some cases there is some confusion over who should be listed as the appellant and who as the respondent. This confusion is primarily the result of the presence of multiple docket numbers consolidated into a single appeal that is disposed of by a single opinion. Most frequently, this occurs when there are cross appeals and/or when one litigant sued (or was sued by) multiple litigants that were originally filed in district court as separate actions. The coding rule followed in such cases should be to go strictly by the designation provided in the title of the case. The first person listed in the title as the appellant should be coded as the appellant even if they subsequently appeared in a second docket number as the respondent and regardless of who was characterized as the appellant in the opinion.
  To clarify the coding conventions, consider the following hypothetical case in which the US Justice Department sues a labor union to strike down a racially discriminatory seniority system and the corporation (siding with the position of its union) simultaneously sues the government to get an injunction to block enforcement of the relevant civil rights law. From a district court decision that consolidated the two suits and declared the seniority system illegal but refused to impose financial penalties on the union, the corporation appeals and the government and union file cross appeals from the decision in the suit brought by the government. Assume the case was listed in the Federal Reporter as follows:
  United States of America,
  Plaintiff, Appellant
  v
  International Brotherhood of Widget Workers,AFL-CIO
  Defendant, Appellee.
  International Brotherhood of Widget Workers,AFL-CIO
  Defendants, Cross-appellants
  v
  United States of America.
  Widgets, Inc. & Susan Kuersten Sheehan, President & Chairman
  of the Board
  Plaintiff, Appellants,
  v
  United States of America,
  Defendant, Appellee.
  This case should be coded as follows:Appellant = United States, Respondents = International Brotherhood of Widget Workers Widgets, Inc., Total number of appellants = 1, Number of appellants that fall into the category "the federal government, its agencies, and officials" = 1, Total number of respondents = 3, Number of respondents that fall into the category "private business and its executives" = 2, Number of respondents that fall into the category "groups and associations" = 1.
  Your task is to identify the state of the first listed state or local government agency that is an appellant.
choices: not Alabama Alaska Arizona Arkansas California Colorado Connecticut Delaware Florida Georgia Hawaii Idaho Illinois Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Massachussets Michigan Minnesota Mississippi Missouri Montana Nebraska Nevada New New New New North North Ohio Oklahoma Oregon Pennsylvania Rhode South South Tennessee Texas Utah Vermont Virginia Washington West Wisconsin Wyoming Virgin Puerto District Guam not Panama