From: "Higgins, Cortney" <Cortney_Higgins@omb.eop.gov>

To: Ron Evans/RTP/USEPA/US@EPA

Cc: Donnalee Jones/RTP/USEPA/US@EPA, Sharon Nizich/RTP/USEPA/US@EPA

Date: 09/14/2010 06:08 PM

Subject: Part of E.O. 12866 Review: EPA Staff response to notes from September 10 Chlor Alkali rule

discussion pertaining to NESHAP: Mercury Emissions from Mercury Cell Chlor

‐ Alkali Plants 2060

‐ AN99

Hi Ron,

These changes/additions look good. The only suggested edit is in Change #2, remove "However," from

the last sentence.

Can you send a revised preamble that reflects these changes?

Regards,

Cortney

‐‐‐‐‐ Original Message

‐‐‐‐‐

From: Evans.Ron@epamail.epa.gov [mailto:Evans.Ron@epamail.epa.gov]

Sent: Monday, September 13, 2010 11:05 AM

To: Higgins, Cortney

Cc: Lee, Amanda I.; Lamson.Amy@epamail.epa.gov; Higgins, Cortney;

Jones.Donnalee@epamail.epa.gov; Fann.Neal@epamail.epa.gov; Nizich.Sharon@epamail.epa.gov;

Walton.Tom@epamail.epa.gov

Subject: Re: Notes from September 10 Chlor Alkali rule Discussion

Cortney, based on your conversation with Tom on Friday and our review of Tom's first cut responses, I

suggest we use the following language:

Regarding change 1: Page 5

‐ 19 of the RIA dated 8

‐ 31 summarizes the uncertainties associated with using

a nationally

‐ derived BPT estimate to quantify the impacts in a particular area. we've adapted this

language to develop the sentences below.

The PM2.5 benefit

‐ per

‐ ton estimates used for this rule assume a certain geographic distribution of

emissions reductions, population density, meteorology, exposure and baseline health incidence rates.

To the extent that these attributes differ greatly from those of the Mercury Chlor Alkali facilities, the use

of these $/ton values in combination with emission changes at MCL facilities to estimate PM2.5 co

‐

benefits may lead to higher or lower benefit estimates than if these co

‐ benefits were estimated using

site

‐ specific data.

Regarding change 2. Page 58

‐ Your requested change to reflect we did not do AQ modeling for this rule

is fine and is reflected below in yellow.

Most of the estimated PM

‐ related benefits in this proposed rule would accrue to populations exposed to

higher levels of PM2.5. Using the Pope et al. (2002) study, 85 percent of the population is exposed at or

above the LML of 7.5 μg/m3. Using the Laden et al. (2006) study, 40 percent of the population is

exposed above the LML of 10 μg/m3. It is important to emphasize that we have high confidence in

PM2.5

‐ related effects down to the lowest LML of the major cohort studies. This fact is important,

because as we estimate PM

‐ related mortality among populations exposed to levels of PM2.5 that aresuccessively lower, our confidence in the results diminishes. However, our analysis shows that the great

majority of the impacts occur at higher exposures. This analysis does not include the type of detailed

uncertainty assessment found in the 2006 PM 2.5 National Ambient Air Quality Standard (NAAQS) RIA

because we lack the necessary air quality input and monitoring data to run the benefits model. In

addition, we have not conducted any air quality modeling for this rule. However, the 2006 PM2.5

NAAQS benefits analysis U.S. Environmental Protection Agency, 2006. Final Regulatory Impact Analysis:

PM2.5 NAAQS. Prepared by Office of Air and Radiation. October. Available on the Internet at

http://www.epa.gov/ttn/ecas/ria.html provides an indication of the sensitivity of our results to various

assumptions.

Regarding change 3: Based on the conversation on Friday, you agreed that adding language to discuss

cost uncertainty would be acceptable as an alternative to removing the benefits uncertainty language in

the EO 12866 section. Here is a slightly revised edition from what Tom circulated on Friday which we

propose to include.

The cost analysis is also subject to uncertainties. Estimating the cost conversion from one process to

another is more difficult than estimating the cost of adding control equipment because it is more

dependent on plant specific information. The estimation of cost savings from environmental

compliance cost savings elimination of the mercury process is also uncertain. The numbers were based

on the savings reported by one US facility and some studies from outside the US. The savings might be

greater or smaller than estimated. Likewise, since the electricity savings are dependent on many of the

same factors, they are also uncertain and may be greater or smaller than estimated.

Please let us know if these changes meet the spirit and substance of your conversation with Tom at your

earliest convenience.

Ron Evans

Leader, Air Benefit & Cost Group

HEID/OAQPS/OAR/EPA

Mail Drop C

‐ 439

‐ 02

919

‐ 541

‐ 5488

919

‐ 541

‐ 0839 fax