The Environmental Protection Agency (EPA) is approving most of a State Implementation Plan (SIP) revision submitted by the State of New Hampshire. This revision updates the State regulation containing ambient air quality standards. EPA is approving all the State's updated standards, except the primary annual fine particle (PM<INF>2.5</INF>) standard, which we are conditionally approving because it does not match EPA's current National Ambient Air Quality Standard for PM<INF>2.5</INF>. This action is being taken in accordance with the Clean Air Act.