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 REquirements 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. This rule amends the NOX SIP Call regulations to allow states to revise their SIP Requirements 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. To read or download a copy of the final rule, go to www.epa.gov/airmarkets/final-update-noxsip-call-regulations or http://www.regulations.gov