Control strategy: Sulfur dioxide.

§ 52.1398 Control strategy: Sulfur dioxide. (a) Redesignation to attainment. The EPA has determined that the Billings 2010 sulfur dioxide (SO 2 ) nonattainment area has met the criteria under CAA section 107(d)(3)(E) for redesignation from nonattainment to attainment for the 2010 1-hour SO 2 NAAQS. The EPA is therefore redesignating the Billings 2010 SO 2 nonattainment area to attainment. (b) The EPA is approving the maintenance plan for the Billings nonattainment area for the 2010 SO 2 NAAQS submitted by the State of Montana on December 14, 2015. (c) Redesignation to attainment. The EPA has determined that the East Helena sulfur dioxide (SO 2 ) nonattainment area has met the criteria under CAA section 107(d)(3)(E) for redesignation from nonattainment to attainment for the 1971 primary and secondary SO 2 NAAQS. The EPA is therefore redesignating the East Helena 1971 SO 2 nonattainment area to attainment. (d) Maintenance plan. The EPA is approving the maintenance plan for the East Helena nonattainment area for the 1971 SO 2 NAAQS submitted by the State of Montana on October 26, 2018. [81 FR 28720, May 10, 2016, as amended at 84 FR 47899, Sept. 11, 2019]