Ozone (2015 8-Hour Standard)

Current Status:

Nonattainment – Moderate Area*

Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, Jefferson, Weld and portion of Larimer county

Attainment Deadline

August 3, 2024

*EPA finalized reclassification to Moderate October 7, 2022

Summary

In April 2018, the U.S. Environmental Protection Agency (EPA) finalized designations, with an effective date of August 3, 2018. The Denver Metro/North Front Range Area (DM/NFR) area was designated as a Marginal nonattainment area with an attainment date of August 3, 2021 (based on the three-year average of monitored ozone values from 2018 through 2020). Based on 2018 – 2020 ozone monitoring data the area failed to attain the 2015 Standard by the Marginal area attainment date and, as such, on October 7, 2022 the EPA finalized the reclassification of the DM/NFR nonattainment area to Moderate under the 2015 Standard with an attainment date of August 3, 2024.

State Implementation Plan (SIP) Documents

Serious Area SIP Documents

Title	Date Last Updated

Moderate Area SIP Documents

Title	Date Last Updated
Moderate State Implementation Plan for the DM/NFR Nonattainment Area for the 2015 Ozone National Ambient Air Quality Standard – Adopted by AQCC on December 16, 2022	December 2, 2022
Moderate SIP Executive Summary – Adopted by AQCC on December 16, 2022	December 5, 2022
Draft SIP Chapters Presented to RAQC Board	August 2022
Technical Support Documents	December 2022

Federal Rules and Actions

Infrastructure SIP Approval (85 FR 20165, Apr. 10, 2020)

Implementation Rules

Final Rule (81 FR 62998, Dec. 06, 2018)

Proposed Rule (81 FR 81276, Nov. 17, 2016)

RAQC Comments (Feb. 13, 2017)

Colorado Department of Public Health and Environment (CDPHE) Comments (Feb. 13, 2017)

Classification Rule (83 FR 10376, March 1, 2018)