FACT SHEET
Final Rule - Emissions Monitoring Provisions in State Implementation Plans
Required Under the NOx SIP Call
ACTION
•	On February 26, 2019, the Environmental Protection Agency (EPA) finalized a regulatory action
entitled "Emissions Monitoring Provisions in State Implementation Plans Required Under the NOx
SIP Call." This final rule amends the NOx SIP Call regulations to allow states to establish alternative,
potentially lower-cost monitoring and reporting requirements for certain sources. The amendments
also remove obsolete regulatory provisions and clarify the remaining regulations.
•	The final rule does not substantively alter any other requirements under the NOx SIP Call regulations
beyond the monitoring provisions for certain sources in states that choose to allow their sources to
use alternative monitoring approaches.
•	The final rule is deregulatory in nature and is expected to lead to potentially lower monitoring costs
for some sources in states that choose to revise their State Implementation Plans (SIPs).
BACKGROUND
•	Under the previous NOx SIP Call regulations, all states covered by the NOx SIP call had to include
provisions in their SIPs requiring certain sources to monitor their NOx mass emissions during the
May to September ozone season according to 40 CFR part 75, which generally entails the use of
continuous emission monitoring systems (CEMS).
•	Most of the sources - primarily electricity generating units - must perform part 75 monitoring under
other programs such as the Acid Rain Program and the Cross-State Air Pollution Rule trading
programs. However, some of the sources - primarily industrial facilities - must perform part 75
monitoring only because of the SIP provisions required by the NOx SIP Call regulations.
•	Under current circumstances, alternative forms of monitoring requirements for these remaining
sources can provide adequate assurance that the NOx SIP Call's emissions reductions will remain
"permanent and enforceable" as required to support redesignations of areas to attainment with the
National Ambient Air Quality Standards (NAAQS).
• Accordingly, this final rule amends the NOx SIP Call regulations to allow states to revise their SIPs to
include alternate, potentially lower-cost monitoring requirements in their SIPs for NOx SIP Call
purposes. The increased flexibility provided by this rule can lead to potentially lower monitoring
costs for some sources in states that submit approvable SIP revisions. The amendments leave it
entirely up to states to decide whether to allow alternative forms of monitoring or to make no
changes to their SIPs and continue to require part 75 monitoring for these sources.

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• The proposal for this action was published on September 27, 2018 (83 FR 48751), and the public
comment period closed on October 29, 2018. All comments have been addressed in the preamble
for the final rule.
FOR MORE INFORMATION
•	To read or download a copy of the final rule, go to www.epa.gov/airmarkets/final-update-nox-
sip-call-regulations or http://www.regulations.gov (EPA's electronic public docket and comment
system). Materials for this action can be accessed using Docket ID No. EPA-HQ-OAR- 2018-0595.
The final rule is also available in hardcopy at the EPA Docket Center's Public Reading Room.
•	For further information about this final action, contact David Lifland of EPA's Office of
Atmospheric Programs, Clean Air Markets Division, at (202) 343-9151 or by e-mail at
lifland.david@epa.gov.

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