51.1000—Definitions.

The following definitions apply for purposes of this subpart. Any term not defined herein shall have the meaning as defined in 40 CFR 51.100.
Act means the Clean Air Act as codified at 42 U.S.C. 7401-767 1q. (2003).
Attainment date means the date by which an area, under an approved State implementation plan, is required to attain the PM2.5 NAAQS (based on the average of three consecutive years of ambient air quality data).
Baseline year inventory for the RFP plan is the emissions inventory for the year also used as the base year for the attainment demonstration.
Benchmark RFP plan means the reasonable further progress plan that requires generally linear emission reductions in pollutants from the baseline emissions year through the milestone inventory year.
Date of designation means the effective date of the PM2.5 area designation as promulgated by the Administrator.
Direct PM 2.5 emissions means solid particles emitted directly from an air emissions source or activity, or gaseous emissions or liquid droplets from an air emissions source or activity which condense to form particulate matter at ambient temperatures. Direct PM2.5 emissions include elemental carbon, directly emitted organic carbon, directly emitted sulfate, directly emitted nitrate, and other inorganic particles (including but not limited to crustal material, metals, and sea salt).
Existing control measure means any Federally enforceable national, State, or local control measure that has been approved in the SIP and that results in reductions in emissions of PM2.5 or PM2.5 precursors in a nonattainment area.
Full implementation inventory is the projected RFP emission inventory for the year preceding the attainment date, representing a level of emissions that demonstrates attainment.
Milestone year inventory is the projected RFP emission inventory for the applicable RFP milestone year (i.e. 2009 and, where applicable, 2012).
PM 2.5 NAAQS means the particulate matter national ambient air quality standards (annual and 24-hour) codified at 40 CFR 50.7.
PM 2.5 design value for a nonattainment area is the highest of the three-year average concentrations calculated for the monitors in the area, in accordance with 40 CFR part 50, appendix N.
PM 2.5 attainment plan precursor means S02 and those other PM2.5 precursors emitted by sources in the State which the State must evaluate for emission reduction measures to be included in its PM2.5 nonattainment area or maintenance area plan.
PM 2.5 precursor means those air pollutants other than PM2.5 direct emissions that contribute to the formation of PM2.5. PM2.5 precursors include S02, NOX, volatile organic compounds, and ammonia.
Reasonable further progress (RFP) means the incremental emissions reductions toward attainment required under sections 172(c)(2) and 171(1 ).
Subpart 1 means the general attainment plan requirements found in subpart 1 of part D of title I of the Act.