Clean Air Corridor Emissions Tracking System

The preamble of the RHR defines a CAC as "a region that generally brings clean air to a receptor 

region", and also says, "the requirement to track emissions will enable states to quickly

determine if changes in patterns of emissions will reduce the number of clean air days (defined 

as the average of the 20% clearest days) in any of the 16 Class I areas." The actual requirements 

state that the §309 SIP or TIP must describe and provide for implementation of comprehensive 

emission tracking strategies for CAC to ensure that the visibility does not degrade on the leastimpaired days at any of the 16 Class I areas.

Using the most recent emission inventory data available through the Emissions Data 

Management System (EDMS), WRAP will produce a report for each five-year implementation 

plan revision (2007-8, 2013, and 2018) on the current and projected emissions in the CAC and in 

areas surrounding the corridor and compare these emissions to a 1996 baseline, as part of a larger 

source apportionment exercise managed by the Technical Oversight Committee (described in the 

next section).

The EDMS will have the capability to produce the following special reports in tabular and 

simple plots (i.e., bar graph and pie chart) formats and allow queries of the same information 

including presentation in GIS format, in addition to the standard reports:

 A summary report of the annual summed total emissions for all six source categories and 

all of the pollutants by county/state and tribal lands, as well as for the entire CAC.

 A summary report of the annual summed total emissions for all six source categories and 

all of the pollutants for the same types of political boundaries surrounding the CAC.

 A summary report of the comparison of the annual summed total emissions for all six 

source categories and all of the pollutants for the same types of political boundaries, as 

well as the entire CAC and the corresponding base year total emissions.

The EDMS to be developed is described in a draft technical report to the Emissions Forum: 

Needs Assessment for Evaluation and Design of an Emissions Data Reporting, Management, and 

Tracking System, (EA Engineering, Science, and Technology, June 26, 2003).

As part of the next round of analysis and preparation for regional haze SIPs due in 2007-08, the 

Technical Oversight Committee will be conducting two separate visibility source apportionment 

exercises (described in the WRAP 2003-08 Strategic Plan), integrating analytical results from 

aerosol and meteorological monitoring, air quality modeling, and preparation of emissions 

inventories. These source apportionment exercises will identify the source regions and 

categories causing visibility impairment at Class I areas. As part of those source apportionment 

exercises, the TOC will analyze the changes in emissions for the counties and tribal lands in the 

CAC, as well as those surrounding the CAC. Better emissions inventory data is expected to be 

available each time, as the TOC iterates through these 2 exercises. Specific results from each of 

the source apportionment exercises will address emissions growth both inside and surrounding 

the CAC, as well as the impact on visibility at affected Class I areas.