### From: "Higgins, Cortney" <Cortney_Higgins@omb.eop.gov> To: Keith Barnett/RTP/USEPA/US@EPA Cc: Charlotte Bertrand/DC/USEPA/US@EPA Date: 08/05/2010 10:53 AM Subject: Redline Comments on PC preamble

Hi Keith,

Attached are redline comments on the PC preamble

– these comments are in the (d)(4) section and the discussion of GHG regulations.

Please let me know if you have any questions. Regards, Cortney (See attached file: RedlineComments_0805_PCPreamble.pdf)Page **71** of **435**

adverse health effects due to concurrent exposure to other HAPs with similar biological endpoints, from either the same or other source categories, where the concentration of the threshold pollutant emitted from the given source category is below the threshold; the potential impacts on ecosystems of releases of the pollutant; and reductions in criteria pollutant emissions

and other co-benefits that would be achieved via the MACT

standard – the decisive factor here. Each of these factors is directly relevant to the health and environmental outcomes at which section 112 of the Clean Air Act is fundamentally aimed. If EPA does determine that it is appropriate to set a standard based on a health threshold, we must develop emission standards that will ensure the public will not be exposed to levels of the pertinent HAP in excess of the health threshold, with an ample margin of safety. Since any emission standard under section 112(d)(4) must consider the established health threshold level, with an ample margin of safety, in this rulemaking EPA has considered the adverse health effects of the HAP acid gases, beginning with

HCl. Research indicates that HCl is associated with chronic respiratory toxicity. In the case of HCl, this means that chronic inhalation of HCl can cause tissue damage in humans. Among other things, it is corrosive to mucous membranes and can cause damage to eyes, nose, throat, and the upper respiratoryPage **72** of **435**

tract as well as pulmonary edema, bronchitis, gastritis, and dermatitis. Considering this respiratory toxicity, EPA has established a chronic reference concentration (RfC) for the

inhalation of HCl of 20 μ g/m 3. An RfC is defined as an estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups 25 ) that is likely to be without an appreciable risk of deleterious effects during a lifetime. The development of the RfC for HCl reflected data only on its chronic respiratory toxicity. T he IRIS health assessment

evaluated chronic non-cancer risks and did not include an evaluation of carcinogenic effects (on which there are very limited studies). As a reference value for a single pollutant,

RfC s do not reflect any potential cumulative or synergistic effects of an individual’s exposure to multiple HAPs or to a combination of HAPs and criteria pollutants. Similarly, an RfC evaluation does not focus on potential environmental impacts. With respect to the potential health effects of HCl, we know the following:

1. Chronic exposure to concentrations at or below the RfC is not expected to cause chronic respiratory effects;

25 “Sensitive subgroups” may refer to particular life stages, such as children or the elderly, or to those with particular medical conditions, such as asthmatics. Comment [A1]: Please provide citations (footnote is fine and link to IRIS file)

Comment [A2]: Not sure this is true

. The RfC setting process looks at all the potential adverse effects and then picks the one of greatest concern (eg effects at lowest level) to protect against all effects. Thus suggest deleting this as the RfC is protective of all the endpoints.

Comment [A3]: The R fC is for chronic effects, thus it wouldn’t include acute exposure. Deleted: It did not take into account effects associated with acute exposure, and, in this situation, t Deleted: did not evaluate the potential carcinogenicity of HCl Deleted: the Deleted: a lso did not Deleted: As the RfC calculation focused on health effects, it did not take into account the potential environmental impacts of HCl.Page **73** of **435**

2. Little research has been conducted on its carcinogenicity. The one occupational study of which we are aware found no evidence of carcinogenicity;

3. There is a significant body of scientific literature addressing the health effects of acute exposure to HCl (California Office of Health Hazard Assessment, 2008. Acute Toxicity Summary for Hydrogen Chloride, http://www.oehha.ca.gov/air/hot_spots/2008/AppendixD2_ final.pdf#page=112 EPA, 2001). However, we currently lack information on the peak short-term emissions of HCl from cement kilns which might allow us to

determine whether a chronic health-based emission standard for HCl would ensure that acute exposures will not pose health concerns.

4. We are aware of no studies explicitly addressing the toxicity of mixtures of HCl with other respiratory irritants. However, many of the other HAPs (and criteria pollutants) emitted by cement kilns also are respiratory irritants, and in the absence of information on interactions, EPA assumes an additive cumulative effect (Supplementary Guidance for Conducting Health Risk Assessment of Chemical

Mixtures. Comment [A4]: Do we know of any cases where the acute exposure level is less than the chronic level? Typically the chronic value is more protective than the acute value and we would expect the same here so if we actually consider the science we know that at a minimum the chronic value would be protective for acute exposures. In fact it would be a conservative value. Thus please revise using what we know about the exposure sciences and health effects.Page **74** of **435**

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=20 533). Cement kilns also emit other acid gases along with HCl, including chlorine (Cl 2 ), HCN and hydrogen fluoride (HF), all of which are HAPs. Like HCl, these HAP gases have established chronic health thresholds below which they are not expected to pose any significant risk of chronic respiratory effects, have no evidence to suggest that they may pose carcinogenic effects, and have an established body of literature regarding acute respiratory health effects. They are also controlled during the process of controlling HCl emissions from cement kilns using a wet scrubber. As such, their health impacts must be taken into account when considering a

health-based emission limit for HCl. In the 2006 final rule, EPA did not set any standard for

HCl. 26 The Agency reasoned that no further control was necessary

for Portland cement emissions of HCl because HCl is a “health threshold pollutant” and human health is protected with an ample margin of safety at current HCl emission levels. 71 FR at

26 Although the decision not to set a standard in 2006 was based on the authority of section 112(d)(4), we note that the statute in fact states: “the Administrator may consider such threshold level, with an ample margin of safety, when establishing emission standards under this subsection.” Section 112(d)(4), emphasis added.Page **75** of **435**

76527. Underlying this conclusion was EPA’s analysis of a tiered screening study of dispersion modeling of cement facilities’ worst-case and actual HCl emissions. This study wasconducted by the Portland Cement Association for about twothirds of operating U.S. cement plants. Dispersion modeling results were evaluated against the RfC for HCl. 27 The screening analysis involved making conservative assumptions regarding HCl emission concentrations and plants’ operating conditions (greater concentrations than known to be emitted and perpetual operation at maximum capacity). All plants in the analysis, with five exceptions, had HCl levels well below a Hazard Quotient (HQ) level of 1.0, the ratio of exposure (or modeled concentration) to the health reference value or threshold level. The remaining five plants in the analysis had HQ levels greater than 1.0 assuming maximum emissions, but less than 1.0 when their actual emissions were used in the dispersion models. Id.

at 76528-29. At proposal of these amendments, recognizing that the 2006 determination was deficient, if for no other reason because it failed to establish any emission standard whatever, EPA

27 In the previous study EPA also evaluated dispersion modeling results against an acute exposure guideline level ( AEGL) below which acute effects would not be expected to occur. However, even given the uncertainties mentioned for short term HCl emissions, that analysis indicated that chronic effects would be of the most concern.Page **76** of **435**

conducted its own analysis to determine what numerical standard for HCl would be necessary to at least assure that, for the sources in the controlled category or subcategory, persons exposed to emissions of HCl would not experience the adverse

health effects on which the threshold is based. In order to determine this level, in the proposed rule we conducted a risk analysis of the same 68 facilities analyzed by PCA using a screening level dispersion model (AERSCREEN). Using site specific stack parameters and conservative meteorological conditions (taken from the PCA analysis), the AERSCREEN modeling predicted the highest long term ground level concentration surrounding each facility. The results of this analysis indicated that an HCl emission limit of 23 ppmv or less (an order of magnitude higher than the MACT standard) would result in no exceedances of the RfC for HCl for any of the facilities

assessed. 28 Based on further consideration, EPA now believes that the 2006 PCA study and analysis have several serious deficiencies. First of all, not all cement plants were evaluated (the PCA study covered about two thirds of the plants in the source category), and among those not evaluated were cement plants with

28 Derivation of a Health-Based Stack Gas Concentration Limit for HCl in Support of the National Emission Standards for Hazardous Air Pollutants from the Portland Cement Manufacturing Industry, April 10, 2009. Comment [A5]: Not sure what exactly constitutes a serious deficiency. Is the concern that the facilities are not representative of potential worst case. If so, please be more clear.Page **77** of **435**

the most likelihood of posing risk at ground level from HCl emissions due to use of positive pressure baghouses with monovents or multiple short stacks. Secondly, the analysis did not consider the impacts of the co-emitted acid gases, an important consideration in determining an ample margin of safety. In addition, no data were provided, nor do we have data, on other pollutants in the vicinity of these cement facilities, or background concentration data for HCl to determine cumulative impacts of HCl emissions for these

facilities. 29 EPA’s analysis of 2009 could not improve on the PCA study, given the lack of robust emissions data for Cl 2 , HF, and HCN, and the lack of any additional data for the cement kilns not included in the original study. As a result, EPA cannot ensure that the resulting derivation of 23 ppmv as a possible health-based emission standard for HCl would result in chronic ambient levels of acid gases that would not pose significant health risks. EPA has not received any data since proposal that would allow us to extend that analysis to cover all acid gases and all facilities.

29 It should be noted that large amounts of site-specific information both on kiln operation and local meteorological information is needed to obtain meaningful results from AERSCREEN and other dispersion models. This information is in the ready possession of the industrial sources themselves, but for unknown reasons, was not provided by industry to EPA either as part of the 2006 PCA analysis or in response to subsequent data solicitations by EPA. Comment [A6]: Has EPA asked for this?Page **78** of **435**

In addition to potential health impacts, EPA has evaluated the potential for environmental impacts when considering whether to exercise discretion under section 112(d)(4). When HCl gas encounters water in the atmosphere, it forms an acidic solution of HCl. In areas where the deposition of acids derived from emissions of sulfur and nitrogen oxides are causing aquatic and/or terrestrial acidification, with accompanying ecological impacts, the deposition of HCl could exacerbate these impacts. Being mindful of the explicit legislative history, and in keeping with past EPA practice, it is appropriate to consider potential adverse environmental effects in addition to adverse health effects when setting an emission standard for HCl under section 112(d)(4). The co-emissions of HF, HCN, and Cl 2 from cement kilns could serve to further aggravate these environmental acidification impacts impacts but at this time EPA has no data to support this claim

. Although the PCA analysis did not include an assessment of potential environmental effects, for the 2006 final Portland cement rule, EPA conducted its own analysis of potential effects of cement kilns’ HCl emissions to wildlife, aquatic life, and other natural resources. The Agency concluded at the time that acute and chronic exposures to expected HCl concentration around cement kilns are not expected to result in adverse environmentalPage **125** of **435**

73 FR at 34,084. These concerns were specifically related to the Prevention of Significant Deterioration and title V permitting programs and the unmanageable permitting burden that we anticipated would arise should GHGs become subject to these programs as a result of regulation under the Act. Since that time, we have issued regulations for GHG emissions under the CAA through the light duty vehicle rule (75 FR 25324, (May 7, 2010)) and have finalized the greenhouse gas “tailoring” rule ( 75 FR 31514 (June 3, 2010)) and the Johnson

memo Reconsideration (75 FR 17004 (April 2, 2010)). As a result of these actions, as of January 2, 2011, GHGs will become "subject to regulation" under the Act. Accordingly, the Agency has now finalized a framework addressing the concerns that were the basis of our decision not to propose standards of performance for GHG emissions from this industry at the time we proposed this 8-year review action. Today’s final rule does not include a standard of performance for GHG. There are two reasons for this. First, we did not propose such a standard. Promulgating such a standard without providing opportunity to comment on it would not be a logical outgrowth of the proposal and would, accordingly, violate the norms of notice and comment rulemaking **.** Second, we do not yet have adequate information about GHG emissions and control strategies for the Portland cement industry. This Comment [A7]: How does this statement comport with the statements below about emissions and that there are cost-effective GHG controls for cement kilns?Page **126** of **435**

information forms the basis of standards of performance, which must take into account achievability and cost of such controls. This is not the end of the matter. To the contrary, based on our current knowledge we believe that it may be appropriate for the Agency to set a standard of performance for GHGs. We have historically declined to propose standards for a pollutant where it is emitting in low amounts or where we determined that a BDT analysis would result in no control. National Lime

Assoc’n v. EPA , 627 F.2d at 426. Based on current information we do not believe such circumstances are present here. Without prejudging the outcome of a future regulatory process, we note the following considerations. First, Portland cement is one of the largest stationary source categories of GHG emissions, ranking as the third highest

U.S. source of CO 2 emissions. Second, based on our initial evaluation it appears that there are cost-effective control strategies for this source category that would provide an appropriate basis for establishing a standard of performance for GHG emissions. See 73 FR 44491, July 30, 2008. These control strategies include, for example, energy efficiency measures, reductions in cement clinker content, and raw materials substitution. There may be other cost-effective controls as

well. Comment [A8]: Please explain what is meant by this? The FR notice points to a report titled “U.S. EPA (2008), Air Pollution Controls and Efficiency Improvement Measures for Cement Kiln. Final Report.” – where can the reader find this?

Comment [A9]: Would these changes also reduce HAP?