The Environmental Protection Agency (EPA) is approving elements of State Implementation Plan (SIP) submissions from New Hampshire regarding the infrastructure requirements of the Clean Air Act (CAA or Act) for the 2010 sulfur dioxide National Ambient Air Quality Standards (NAAQS). EPA is also updating the classification for two of New Hampshire's air quality control regions for sulfur dioxide based on recent air quality monitoring data collected by the state. Last, we are conditionally approving certain elements of New Hampshire's submittal relating to prevention of significant deterioration requirements. The infrastructure requirements are designed to ensure that the structural components of each state's air quality management program are adequate to meet the state's responsibilities under the CAA.