### Fw: Interagency Review of EPA SOx /NOx Secondary Standard Jan King to: Sherry Russell 07/12/2011 09:14 AM Jan King Regulatory Development and Policy Analysis Group phone: (919) 541-5665 fax: (919) 541-2664 Mailcode: C404-05
----- Forwarded by Jan King/RTP/USEPA/US on 07/12/2011 09:14 AM -----

From: "Laity, Jim" <James

_ A.

_ Laity@omb.eop.gov> To: Lydia Wegman/RTP/USEPA/US@EPA Cc: Karen Martin/RTP/USEPA/US@EPA, John Hannon/DC/USEPA/US@EPA, Jan King/RTP/USEPA/US@EPA Date: 07/07/2011 06:47 PM Subject: RE: Interagency Review of EPA SOx/NOx Secondary Standard

Thx Lydia/karen. Just to clarify, when you say some areas will receive directionally more protection, you mean this hypothetically, based on the results of applying the proposed secondary standard relative to the existing secondary standard. In actual practice there will be no effect, since areas are already required to meet the primary standard and there are no new implementation requirements associated with meeting the secondary standard. This was my previous understanding. -- jim -----Original Message----- From: Lydia Wegman [mailto:Wegman.Lydia@epamail.epa.gov] Sent: Thursday, July 07, 2011 6:07 PM To: Laity, Jim Cc: Karen Martin; John Hannon; Jan King Subject: Fw: Interagency Review of EPA SOx/NOx Secondary Standard

Jim, Karen wrote a quick response to your questions. I hope these are helpful. The proposed 1-hr secondary standard of 75 ppb would generally be more stringent than the current 3-hr, 500 ppb secondary standard, although the relative degree of stringency would vary due to differences in temporal air quality patterns in different areas. The proposal notice proposes to keep the current 3-hr standard and to add the 1-hr standard. The current secondary standard for NO2 is an annual standard of 53 ppb, which is the same as the annual NO2 primary standard. The proposal notice proposes to keep the current annual standard and to add the 1-hr standard of 100 ppb, which is identical to the 1-hr NO2 primary standard set in 2010. The effect of setting secondary standards identical to the new 1-hr primary standard would be to recognize the ecological benefit of the reductions in oxides of nitrogen and sulfur that will result fromstrategies to meet the ne w 1- h r standards

. I t would not result in an y areas receiving less protection, while some areas will receive directionally more protection than that afforded by only the current secondary standards.

From: "Laity, Jim" <James_A._Laity@ omb.eop.gov> To: Karen Martin/RTP/USEPA/US@EPA, Lydia Wegman/RTP/USEPA/US@EPA Date: 07/07/2011 05:17 PM Subject: FW: Interagency Review of EPA SOx/NOx Secondary Standard

Lydia, Karen, Could you give me a quick answer to the questions below: For Sox, Is the proposed secondary NAAQS of 75 ppb over 1 hour more stringent than the current .5 ppm (500 ppb) over 3 hours? Are you also keeping the current secondary standard? What is the practical effect of setting the secondary NAAQs for NOx and SOx at the same level as the primary? i.e. Are there areas that will receive less protection or more protection? What is the current NAAQS for NOx? According to EPA’s website ( http://www.epa.gov/air/ criteria.html), it appears that the secondary NAAQS for NOx is already the same as the primary? So, what is the effect of the revised proposal? Thanks, jim