40 CFR § 58.50 - Index reporting.

---
identifier: "/us/cfr/t40/s58.50"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 58.50 - Index reporting."
title_number: 40
title_name: "Protection of Environment"
section_number: "58.50"
section_name: "Index reporting."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "C"
subchapter_name: "AIR PROGRAMS"
part_number: "58"
part_name: "AMBIENT AIR QUALITY SURVEILLANCE"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 7403, 7405, 7410, 7414, 7601, 7611, 7614, and 7619."
regulatory_source: "44 FR 27571, May 10, 1979; 59 FR 41628, Aug. 12, 1994, unless otherwise noted."
cfr_part: "58"
---


# 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]