[Code of Federal Regulations] [Title 40, Volume 5] [Revised as of July 1, 2008] From the U.S. Government Printing Office via GPO Access [CITE: 40CFR58.50] [Page 228] TITLE 40--PROTECTION OF ENVIRONMENT CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PART 58_AMBIENT AIR QUALITY SURVEILLANCE--Table of Contents Subpart F_Air Quality Index Reporting Sec. 58.50 Index reporting. (a) The State or where applicable, local agency shall report to the general public on a daily basis through prominent notice an air quality index that complies with the requirements of appendix G to this part. (b) Reporting is required for all individual MSA with a population exceeding 350,000. (c) The population of a MSA for purposes of index reporting is the most recent decennial U.S. census population. [71 FR 61302, Oct. 17, 2006]