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Air Quality Improvement Plans

Emission reductions from control measures the District plans to adopt are estimated and accounted for in State Implementation Plans (SIPs), which are legally binding documents. The District develops new regulations and revises existing regulations to implement SIP actions.

Elements of Nonattainment Area Planning

Section 110 of the Clean Air Act requires states that fail to meet the NAAQS for a criteria pollutant to develop a SIP to describe how the state will attain and maintain the NAAQS. The entire Washington D.C. metropolitan area, which includes the District and parts of Maryland and Virginia, is currently in nonattainment of the federal NAAQS for ozone and PM2.5, and thus is required to develop SIPs for those pollutants.

DDOE coordinates with numerous agencies and organizations throughout the region to brainstorm and adopt similar emission reduction strategies as part of the SIP process. Main elements of SIP development include:

Emission Inventories - The first step towards understanding the air quality of an area is to develop an inventory of emissions. Emission inventories act as an air "audit" or "snapshot" for a given season or year. Different kinds of inventories (base year, projected year; point source, area source) and emission estimation methodologies are used to characterize emissions from sources that contribute to different air quality problems.

Assessment & Modeling - Data from emissions inventories and monitoring is used by modelers to forecast future emissions under different emission reduction and cost scenarios. Types of analysis included in a SIP include attainment demonstrations, emission budgets, and uniform rate of progress determinations. Accurate, science-based monitoring and modeling results are critical to the development of reliable and defensible SIPs.

Transportation Conformity - Emissions from transportation sources such as cars, trucks, buses, trains, planes, and construction vehicles are a main contributor to air pollution in the District. The Clean Air Act requires that transportation planning activities be considered during the SIP process to ensure they are consistent with air quality goals.

Public Participation - Once the EPA approves a SIP, the plan is enforceable as a law. Before a law is passed, stakeholders have the opportunity to influence the decision-making process by submitting comments in response to public notice of comment periods or hearings. Stakeholders generally include members of the public, public interest groups, and permitted entities.

A record of the history of changes to the District's all-encompassing SIP, with a record of changes to the air quality regulations since they were established in 1984, can found in Title 40, Subpart J of the Federal Register.

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