On June 22, 2010, EPA promulgated a revised 1-hour, 75 ppm, sulfur oxide (SO2) primary standard. The SO2 primary standard was revised to provide requisite protection of public health. Under Section 110 (a) of the Federal Clean Air Act, States after promulgation of a national primary ambient air quality standard (or any revision thereof), must implement plans to attain or maintain the standard. The State Implementation Plan (SIP) must demonstrate, through refined air quality modeling, that all sources contributing to or having the potential to contribute to monitored and modeled violations will be sufficiently controlled to ensure timely attainment and maintenance of the new SO2 standard.
The primary SO2 final rule (1) replaces the 24-hour and annual standard, (2) establishes a new 1-hour standard (3) utilizes the 3-year average of the 4th highest daily maximum 1-hour concentration, (4) establishes new requirements for the SO2 monitoring network, and (5) finalizes conforming changes to the Air Quality Index (AQI).
SO2 SIP Timeline
SO2 Notes and Presentation
Stakeholder Meeting Record
September 9, 2011