U.S. EPA FACT SHEET

Sacramento Metro Area 1-Hour Ozone Clean Data Determination

October 3, 2012

Summary of Action

EPA is determining in a final rulemaking that the Sacramento Metro severe 1-hour ozone
nonattainment area (Sacramento Metro Area) attained the 1979 1-hour ozone national
ambient air quality standard (1-hour ozone NAAQS or standard) in 2009, based on
complete, quality-assured and certified ambient air quality monitoring data for the period
2007-2009, and is continuing to attain that standard.

Background

•	The Sacramento Metro Area was designated as nonattainment for the 1-hour standard by
operation of law on November 15, 1990. In the mid 1990s, EPA reclassified the area to
severe following a voluntary request by the local air districts and the California Air
Resources Board (CARB). The deadline for severe areas to attain was November 15,
2005. Sacramento failed to attain in 2005, but was able to demonstrate 1-hour attainment
with monitoring data from 2007-2009, excluding three days of data in 2008 due to
wildfire exceptional events. The area has continued to attain the 1-hour ozone standard.

•	Since setting the 1979 0.12 parts per million (ppm) ozone NAAQS (revoked in 2005),
EPA has revised the ozone standard twice. The Sacramento Metro Area is severe
nonattainment for both the 1997 8-hour (0.08 ppm) and 2008 8-hour (0.075 ppm) ozone
NAAQS.

EPA's May 2011 Proposed Action and Today's Action

•	On May 18, 2011, EPA published in the Federal Register (76 FR 28696) a proposal to
terminate 1-hour ozone section 185 requirements for the Sacramento Metro Area based
on our determination that the districts' and state's demonstration showed that two
redesignation criteria were met: 1) the area has 1-hour ozone monitoring data that meets
the standard, and 2) the clean data were due to permanent and enforceable emissions
reductions in the area.

•	The clean data portion of the proposal relied on EPA's concurrence with the state and
local districts that monitoring data for three days in 2008 should be excluded from
consideration due to wildfire exceptional events.

•	During the proposal's public comment period, EPA received comments that supported
the clean data determination and we are finalizing that determination today.


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•	We are in the process of responding to comments regarding the section 185 termination
aspect of the proposal, and we plan to address that termination in future rulemaking.

•	Today's action does not relate to either the 1997 or the 2008 ozone NAAQS.

Next Steps

•	Today's action will be published in the Federal Register and will add regulatory text in
the Code of Federal Regulation (CFR) codifying the clean data determination, in 40 CFR
52.282.

For More Information:

http://www.epa.gov/region9/air/actions/ca.html


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