Section 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 metropolitan statistical area for purposes of index reporting is the latest available U.S. census population. 71 FR 61302 , Oct. 17, 2006, as amended at 80 FR 65466 , Oct. 26, 2015