               Environmental Protection Agency (EPA): Final Rule
Data Requirements Rule for the 2010 1-Hour Sulfur Dioxide (SO2) Primary National Ambient Air Quality Standard (NAAQS)
                                 RIN 2060-AR19
General Comments

   1. Reviewer recommends providing the marginal benefits and costs to choosing the 2,000 tpy (both inside and outside the 1m population area) over the other options provided within the proposed rule.  Specifically, provide the cost per ton of each option, including 1,000 tpy/2,000 tpy; 2,000 tpy/5,000 tpy; 3,000 tpy (both within and outside the 1m population area); 3,000 tpy/10,000 tpy; and 5,000 tpy (both within and outside the 1m population area).
   2. Reviewer recommends clarifying why a preliminary list of source areas is required to be submitted instead of allowing states to provide a preliminary list of source areas if the state believes that would ensure that they met the required deadlines, especially since EPA states they are consulting with air agencies regarding the source areas that the final rule will characterize.  
   3. Reviewer recommends clarifying federally enforceable requirements that limit source emissions to less than 2,000 tpy.
   4. Reviewer recommends clarifying how compounding multiple sources for modeling is treated to ensure that an overly conservative model is not developed. 
   5. Reviewer recommends providing additional clarification whether the use of dispersion modeling is appropriate for attainment or nonattainment designations.
   6. 
   
Specific Comments

   1. Page 7. Reviewer recommends modifying the sentence below to more strongly convey that the approach shall not be used for other NAAQS pollutants.
         a. ". . . EPA believes that the approach set forth in this rule directing air agencies to gather additional data to characterize ambient air in the vicinity of larger SO2 sources is uniquely suited for implementation of the 1-hour SO2 NAAQS, and the Agency does not currently anticipate it to be used for other NAAQS pollutants." 
   2. Page 22-23.  Reviewer recommends modifying the two sentences that start with "Likewise here, the EPA is not yet . . ." to state:
         a. "Likewise here, the EPA is not yet taking any action to apply modeling regarding any decision of whether an area is or is not meeting the NAAQS.  In any event, we note that . . ." 
   3. Page 65-67.  Reviewer recommends clarifying EPA's response to comments on EPA's legal authority to review modeling procedures that could affect compliance with regulatory requirements.  Also, please discuss, if appropriate, whether any commitments or "presumptive acceptance" based on a reasonable time-frame that would allow states to comply with EPA regulations should be included.
Typographical Comments

   1. Reviewer recommends removing "or not" whenever "whether or not" is stated within the document.
