Comment submitted by Edmund Crouch, Cambridge Environmental Inc.

The 1st draft REA for ozone at http://www.epa.gov/ttn/naaqs/standards/ozone/s_o3_2008_rea.html has within it references to two documents that are supposed to be present on the same web page. They are: At pages 3-25 and 4-18: Simon, H., Baker, K., Possiel, N., Akhtar, F., Napelenok, S., Timin, B., Wells, B. (2012) Model-based rollback using the higher order direct decoupled method (HDDM). At pages 4-19, 5-59, and 8-52: Wells, B., Wesson, K., Jenkins, S. (2012). Analysis of Recent U.S. Ozone Air Quality Data to Support the O3 NAAQS Review and Quadratic Rollback Simulations to Support the First Draft of the Risk and Exposure Assessment. Neither of these documents is present on that web page. Please make them available. In addition, the REA makes reference to Appendices 4-A (pages 8-7,8-25, 8-38, 8-46 twice), and Appendix 4-B (on page 4-6), neither of which is present in the document or on the web page. I think the reference to Appendix 4-B should be Appendix 5-B, but have not examined the "Appendix 4-B" material. If further appendices are intended, please make them available; or indicate the location of the referenced materials. Thank you.