1

MEMORANDUM

Date: June 18, 2015

Subject: Wool Fiberglass RTR Ample Margin of Safety – Analys is and Controls for the Final

Amendments

From: Susan Fairchild, EPA/OAQPS/SPPD/MMG

To: EPA Air Docket EPA-HQ-OAR-2010-1042

I. Introduction

The purpose of this memorandum is to present inform ation used in the ample margin of safety analysis for the U.S. Environmental Protection Agen cy’s (EPA’s) residual risk review of the national emission standards for hazardous air pollutants (NE SHAP) for the Wool Fiberglass Manufacturing Source Category (40 CFR part 63, subpart NNN) in ac cordance with section 112(f)(2) of the Clean Air Act (CAA).

Wool fiberglass is produced by melting raw material s (silica sand, soda ash, borides, other minerals, and cullet) in a high temperature furnace and transferring the molten glass in a thin stream to either a rotary spin (RS) or a flame attenuation (FA) line for fiber formation. If the end product is bonded wool fiberglass, the product must be coated with a binder. Some wool fiberglass facilities that produce bonded wool fiberglass use a phenol-formald ehyde (PF) binder, but the industry has largely phased out the use of such binders in favor of non- HAP binding agents. Wool fiberglass products are primarily used as thermal and acoustical insulation for buildings, automobiles, aircraft, appliances, ductwork, and pipes. For more information on wool f iberglass manufacturing, see the preamble discussion in the November 25, 2011 proposal (76 FR 72776).

Section 112(f)(2) of the CAA requires us to determi ne, for source categories subject to certain MACT standards, whether those emissions standards p rovide an ample margin of safety to protect public health. As specified in CAA section 112(f)(2)(A), if MACT s tandards that apply to a source category emitting a HAP that is “classified as a k nown, probable, or possible human carcinogen do

not reduce lifetime excess cancer risks to the indi vidual most exposed to emissions from a source in the category or subcategory to less than one-in-one million,’’ the EPA must promulgate residual risk standards for the source category (or subcategory) as necessary to provide an ample margin of safety to protect public health. Section 112(f)(2) of the CAA expressly preserves our use of the two-step process for developing standards to address any res idual risk and our interpretation of “ample margin of safety” developed in the Benzene NESHAP. The fir st step in this process is the determination of acceptable risk. This determination “considers all health information, including risk estimation uncertainty, and includes a presumptive limit on MI R [cancer] of approximately 1-in-10 thousand [ i.e., 100-in-1 million]’’ (54 FR 38045). In the second st ep of the process, the EPA sets the standard at a level that provides an ample margin of safety ‘‘in consideration of all health information, including the number of persons at risk levels high er than approximately 1-in-1 million, as well as other relevant factors, including costs and economi c impacts, technological feasibility, and other factors relevant to each particular decision’’ ( Id. ).2

. The first step in this process is the determinati on of acceptable risk. Under this first step,

Tt he EPA conducted two information collection request s (ICRs) that included all wool fiberglass facilities currently operating in the U.S. The firs t ICR was voluntary and allowed companies to perform HAP emissions testing on a subset of facili ty operations, if the facilities were able to demonstrate that the subset was representative of t he untested subset. Emissions testing on bonded lines were conducted using EPA Method 318, for phen ol, formaldehyde and methanol. Companies were also allowed to submit MACT-compliance testing (which is only for formaldehyde) with binder formula data on the phenol/formaldehyde and the met hanol/formaldehyde ratios to estimate emissions of phenol and methanol. Emissions testing on the furnaces was conducted using EPA Method 5 for PM, Method 29 for total chromium compo unds and Method 0061 to measure hexavalent chromium (in order to speciate the perce ntage of the total chromium that is emitted in the hexavalent state). The risk drivers for this source category are formaldehyde and hexavalent

chromium. Test results were typically presented as three test runs and provided in units of mass of pollutant per mass of production (e.g., lbs of HAP/ ton of glass pulled).

The ICR responses from all the facilities were comp iled in the project database and included information on each facility, process, process equi pment, control equipment, costs, and HAP emissions. The second ICR requested specific inform ation about furnaces and required that all

facilities that had not submitted chromium and hexa valent chromium (Cr 6+ ) test data conduct and submit Method 29 and Method 0061 testing. The EPA then used all available data (which is a combination of both new and existing test data ) to populate the wool fiberglass residual risk mode ling file. The risk assessment, which evaluated both act ual and MACT- allowable emissions, can be found

in the October 2014 Draft Residual Risk Assessment for the Mineral Wool Produ ction and Wool Fiberglass Manufacturing Source Categories in Support of the June 2015 Final Rule in the dD ocket. Generally, if risks are found to exceed 100-in-1 mi llion, we consider this unacceptable and act to reduce risk to acceptable levels by requiring emiss ion reductions of the pollutants responsible for th e risk (i.e., the ‘risk drivers’). If risk is found t o be below 100-in-1 million, we consider risk to be acceptable; for the wool fiberglass manufacturing s ource category, risks were found acceptable at 20-

in-1 million.

The second step of sS ection 112(f)(2) provides for an ample margin of sa fety (AMOS) to protect public health. In this step of the process, the EPA sets the stand ard at a level that provides an ample margin of safety “in consideration of all hea lth information, including the number of persons at risk levels higher than approximately 1-in-1 millio n, as well as other relevant factors, including cos ts and economic impacts, technological feasibility, an d other factors relevant to each particular

decision.” For the AMOS determination, the EPA searched for technologies and associated costs reviewed the industry and the technical literature to determine if cost-effective means are available

that would further reduce emissions of hexavalent c hromium or formaldehyde. The data search

included similar sources both within and outside th e source category for technologies that would reduce these emissions. Because the industry was in the process of eliminating the use of formaldehyde using non-HAP binders, and had already reduced formaldehyde emissions by up to 95 percent of the MACT levels, EPA considered this raw material substitution already underway as an appropriate strategy to further reduce risk from fo rmaldehyde. The EPA focused risk reduction efforts on technologies that would further reduce emissions of chromium emissions , especially Cr 6+

.

Similar process associated with Cr 6+ emissions within three industries were found: chro mium electroplating, the metallurgical industry and the electric utility industry. The costs of control3

technologies for those industries were evaluated, a nd two technologies (reducing the operational life cycle for specific process equipment and installati on of sodium hydroxide [NaOH] scrubbers) were

found to have reasonable cost effectiveness in term s of dollars per pound of pollutant removed. The wool fiberglass glass-melting furnace process param eters were compared to those in the chromium electroplating, metallurgical and electric utility industries. These technologies were evaluated, taki ng into consideration costs, energy, safety and other relevant factors (such as adverse environmental effects) to determine whether risk, although accept able, could be further reduced to meet a level achieving an AMOS, using the available cost effecti ve emission reduction approaches and that these emission reduction approaches are transferable to t he furnace operations. 1

II. Identification of Subpart NNN Risk Driver HAP a nd Processes

The November 2011, February 2013, and October 2014 draft residual risk assessments were based on actual emissions currently emitted by indu stry and are summarized as follows:

2011 proposal risk results  MIR = 40 (formaldehyde*, Cr 6+ ) (based on actual emissions) 11,641 people exposed t o cancer risk >10-in-1 million 849,000 people exposed to cancer risk >1-in-1 mi llion HI = 0.2 (formaldehyde) HQ = 30 (formaldehyde – based on REL) Cancer incidence = 0.05 (52% formaldehyde, 47% C r 6+ )

2013 proposal risk results  MIR = 20 (formaldehyde); (based on actual emissions) 1,800 people exposed to cancer risk >10-in-1 million 650,000 people exposed to cancer risk >1-in-1 m illion HI = 0.2 (formaldehyde) HQ = 30 (formaldehyde – based on REL) Cancer incidence = 0.04 (64% formaldehyde, 35% C r 6+ )

2014 proposal risk results  MIR = 20 (formaldehyde and Cr 6+ ); (based on actual emissions) 6,900 people exposed to cancer risk >10-in-1 million 1,200,000 people exposed to cancer risk >1-in-1 million HI = 0.2 (formaldehyde) HQ = 30 (formaldehyde – based on REL) Cancer incidence = 0.04 (64% formaldehyde, 35% C r 6+ )

The EPA also analyzed post-MACT risks based on the proposed limits in the 2014 supplemental proposal. Below is a summary of the results of the post-MACT risk assessment and details of the analysis can be found in the October 2014 Draft Residual Risk Assessment for the Mineral Wool Production and Wool Fiberglass Manufacturing Source Categories.

1 See the following memoranda available in docket EP A-HQ-OAR-2010-1042: Control Cost Evaluation for Glass-Melting Furnaces, Section 112( d)(6) Technology Review for Wool Fiberglass NESHAP, and Development of Background Information o n Area Source Emissions Limit - Determination of GACT for Wool Fiberglass Furnaces at Area Sources )

.4

Post-MACT estimated risk results  MIR = 5 0 people exposed to cancer risk >10-in-1 million 21,000 people exposed to cancer risk >1-in-1 mi llion

HI = 0.3 HQ = 7

Following the publication of the November 2014 supp lemental proposal, we did not receive

new actual emissions data and we did not have to re vise our estimate of actual emissions from wool fiberglass manufacturing facilities. Therefore, we did not re-assess the risks from actual emissions f or wool fiberglass manufacturing facilities. The MIR b ased on actual emissions remains at 20-in-1 million with the acute noncancer HQ remaining at 30 for the REL and 1 for the AEGL–1 (formaldehyde). The maximum chronic non-cancer TOSH I value based on actual emissions is 0.1 with emissions of formaldehyde dominating those imp acts, indicating no significant potential for chronic noncancer impacts.

However, Ww e conducted a new assessment of the risks remaining after implementation of

the final rule revisions. The risk assessment took into account the change in the chromium compounds emission limit for gas-fired glass-meltin g furnaces from 0.00006 to 0.00025 pounds of chromium per ton of glass pulled and the actual MACT-allowable emissions of formaldehyde, methanol or phenol from RS lines. The MIR for cance r after implementation of the RTR could be up to 60-in-1 million and is driven primarily by the MACT-allowable formaldehyde emissions with chromium emissions as a secondary risk driver. Thes e post-RTR risks were determined to be acceptable. We used actual emissions from RS lines for the assessment of the risks remaining after implementation of the final standards because, as w e noted in section V.H of the preamble to the final rule, the EPA is not establishing limits under CAA sections 112(d)(2) and (3) for RS lines at this

time. We believe that the data that we relied on in proposing the RS standards are not sufficiently related to current operations or emissions from RS bonded lines and we have issued a CAA section 114 ICR to wool fiberglass facilities to obtain upd ated formaldehyde, methanol, and phenol emissions and process data for RS manufacturing lin es. We will analyze the ICR data and evaluate RTR limits for RS lines at wool fiberglass manufact uring facilities at a future date.

Additionally, based on comments received in respons e to the November 2014 supplemental proposal that indicated that a newly-rebuilt furnac e, which we believe is the likely compliance technology, might not be able to demonstrate compli ance with the proposed chromium emission limit. We re-evaluated the proposed total chromium limit and conducted an assessment of the risk attributable to all HAP for each facility and deter mined that increasing the chromium compound emission limit from 0.00006 to 0.00025 pounds total chromium per ton of glass pulled has a minimal effect on the post-RTR risks because these risks ar e largely driven by formaldehyde emissions. Specifically, at the chromium compounds emission li mit of 0.00025 pounds total chromium per ton of glass pulled, the MIR due to only chromium emiss ions for the source category is 3-in-1 million; whereas, the MIR due to only the MACT-allowable formaldehyde post-RTR emissions for the source category is 60-in-1 million. As noted above, these post-RTR risks were determined to be acceptable. It is important to note that, even though risks are acceptable, the health risks from Cr 6+ emissions from wool fiberglass manufacturing facilities could be much higher in the future without a chromium compounds emission limit. To capture this scenario, we conducted an auxiliary risk analysis in which we assumed all wool fiberglass furnaces emitted Cr 6+ at the same rate as the highest-emitting furnace. The results of the auxiliary risk analysis showed t hat, at the assumed emission rate, four facilities5

would have MIR cancer risks greater than 100-in-1 m illion. The results of the risk assessment are presented in more detail in the final residual risk memorandum titled “Residual Risk Assessment for the Mineral Wool Production and Wool Fiberglass Man ufacturing Source Categories in Support of the June 2015 Final Rule”, which can be found in Do cket ID No. EPA-HQ-OAR-2010-1042.

Risk Uncertainties

Although every effort was made to identify all the relevant facilities and emission points, as well as to develop accurate estimates of the annual emission rates for all relevant HAP, the uncertainties in our emission inventory likely domi nate the uncertainties in our exposure modeling estimates. The chronic ambient modeling uncertainti es are considered relatively small in comparison, since we are using EPA’s refined local dispersion m odel with site-specific parameters and reasonably representative meteorology. If anything, the popula tion exposure estimates are biased high by not accounting for short- or long-term population mobil ity, and by neglecting processes like deposition, plume depletion, and atmospheric degradation. Addit ionally, estimates of the maximum individual risk (MIR) contain uncertainty, because they are de rived at census block centroid locations rather than actual residences. This uncertainty is known t o create potential underestimates and overestimates of the actual MIR values for individual facilities, but, overall, it is not thought to have a signific ant impact on the estimated MIR for a source category.

The acute screening results were purposely biased h igh, considering that they depend upon the joint occurrence of independent factors, such a s hourly emissions rates, meteorology and human activity patterns. Furthermore, in cases where mult iple acute threshold values are considered scientifically acceptable, we have chosen the most conservative of these threshold values, erring on the side of overestimating potential health risks f rom acute exposures. In the cases where these resul ts indicated the potential for exceeding short-term he alth thresholds, we have refined our assessment by developing a better understanding of the geography of the facility relative to potential exposure

locations.

Additional discussion of uncertainties in our risk analysis can be found in Section 5 of the

final risk assessment document titled “Residual Ris k Assessment for the Mineral Wool Production and Wool Fiberglass Manufacturing Source Categories in Support of the June 2015 Final Rule”, which can be found in the rulemaking docket.

III. Ample Margin of Safety Analysis

The main risk drivers for the wool fiberglass sourc e category were formaldehyde and Cr 6+
emissions. Formaldehyde emissions are associated wi th the production of bonded wool fiberglass products that use PF binders and many facilities are continuing to switch their binders and have reduced or eliminated formaldehyde emissions.

Formaldehyde Emissions from Manufacturing Lines

As noted in the preamble to the November 25, 2011 p roposal (76 FR 72777-72778), most facilities have phased out the use of PF binders on bonded lines, and as a result, the wool fiberglass manufacturing industry has significantly reduced or eliminated formaldehyde emissions. Based on the most recent information provided by industry, w e estimate that two facilities have 13 bonded FA manufacturing lines and all of the FA lines are in compliance with the emission limits in the final Formatted: Indent: First line: 0.5"6

rule. Therefore, additional controls are not needed for existing FA lines. The most recent information provided by industry indicates that four companies operate 5 RS bonded lines on which a PF binder is

used. As noted in Section II of this memorandum, we are n ot establishing limits under CAA sections 112(d)(2) and (3) for RS lines in the fina l action because we believe that the data that we relied on in proposing the RS standards are not suf ficiently related to current operations or emission s from RS bonded lines. The EPA has issued a CAA sect ion 114 ICR to wool fiberglass facilities to obtain updated formaldehyde, methanol, and phenol e missions and process data for RS manufacturing lines and we will analyze the ICR dat a and evaluate RTR limits for RS lines at a future date. We believe that deferring the standard s for RS lines, under CAA sections 112(d)(2) and (3), does not impact the risk assessment conducted under CAA section 112(f)(2) because the risk

assessment was based on test data of actual emissio ns of formaldehyde from all the facilities that manufacture wool fiberglass.

As discussed above, sources that use RS lines have been phasing out the use of formaldehyde, but, at the time we conducted the risk assessment, we did not know which lines and facilities were formaldehyde-free. We therefore, included the avail able actual emissions from the RS bonded lines.

We believe that this would be the kind of uncertain ty in emissions datasets used for risk assessments that we discussed in our November 2011 proposal. In that proposal, we explained that there are inherent uncertainties and potential for bias in al l risk assessments, such as uncertainty in emission s datasets (i.e., accuracy of emission values that va ry depending on the source of the data, the degree to which data are incomplete or missing, the degree to which assumptions made to complete the datasets are inaccurate, error in estimating values and othe r factors). We concluded that despite these uncertainties, we believed that our approach, which uses conservative tools and assumptions, ensures that our decision is health-protective (76 FR 72783 -84). Additionally, because we believe that actual formaldehyde emissions would be less than indicated by the emissions test data on which the risk assessment was based (due to the continuing phase o ut of PF binders), we continue to believe that the risk assessment as it relates to formaldehyde is a conservative overstatement of risk and that our

decision to finalize the emission limits for existi ng, reconstructed, and new FA lines, as proposed in 2014, remains health-protective. We note that even though formaldehyde is the driver for the MIR and we are not finalizing emission limits for RS li nes in this action, the post-RTR MIR is equivalent

to the MACT-allowable MIR at 60 in-a-million

Chromium Emissions from Gas-fired Glass-Melting Fur naces

Chromium emissions, including Cr 6+ , are associated with gas-fired glass-melting furna ces and the degradation of chromium refractories in the fur nace. Chromium compounds emissions are a secondary risk driver to formaldehyde, and the curr ent baseline risk is 7-in-1 million. Most, if not all gas-fired glass-melting furnaces are lined with hig h-chromium refractory materials to withstand the extreme temperatures and highly corrosive gases rel eased in the melting process to manufacture wool fiberglass. Due to the extreme operating conditions , the refractories erode over time (i.e., 3 to 10 years – depending on furnace type and design) and a re believed to be the source of most of the

chromium and Cr 6+ emissions. The memorandum “Mechanisms of Chromium Emissions From Wool Fiberglass Glass-Melting Furnaces,” which is availa ble in docket EPA-HQ-OAR-2010-1042, presents a more in-depth discussion of chromium emi ssions from gas-fired glass-melting furnaces.

As discussed in the memorandum for the ample margin of safety to support the November 13, 2014 proposal (Wool Fiberglass RTR Ample Margin of Safety – Analysis and Proposed Formatted: Indent: First line: 0.5"

Formatted: Indent: First line: 0.5"7

Controls, EPA-HQ-OAR-2010-1042-0334), we considere d several process alternatives and control options for reducing chromium emissions from gas-fi red glass-melting furnaces. As discussed in the preamble to the November 13, 2014 proposal (79 FR 6 8021-68022), we initially proposed in 2011

that both the furnace rebuild and the addition of a NaOH scrubber were cost effective options for reducing chromium emissions. At that time, we surmi sed that a wool fiberglass manufacturer would

choose non-chromium refractories with which to rebu ild the furnace. We have since learned from industry that the use of high-chromium refractories is needed to withstand the high internal temperature, reactivity, corrosivity, and erosivity of the gas-fired glass-melting furnace environment

. Consequently, we considered the early replacement of the high-chromium refractory before high

levels of chromium emissions are released as the re fractory degrades as the most likely approach that wool fiberglass manufacturers will take to reduce c hromium emissions from gas-fired glass-melting

furnaces.

IV. Conclusions

The health risks associated with formaldehyde emiss ions from wool fiberglass bonded manufacturing lines and Cr 6+ emissions from glass-melting furnaces were reviewe d. Both of these HAP-emitting processes were the focus of the ample margin of safety analysis because control measures and raw material substitution options appl ied to these processes offer the greatest potential for risk reduction. Industry stakeholders have told us that many facilities are continuing to switch

their binders and have reduced or eliminated formal dehyde emissions. If formaldehyde and Cr 6+ are emitted at the level of the final emission limits, then the resulting MIR could be as high as 60-in-1

million based on MACT-allowable formaldehyde emissions , which we determined is are acceptable. Considering cost and technical feasibility, replacing the high-chromium refractory before degra dation

results in elevated chromium emissions from reducin g the operational life of the gas-fired furnaces from 10 years to 7 years was identified as the most feasible option for increasing providing anthe ample margin of safety for wool fiberglass manufact uring facilities. Commented [DG1]: Winifred, we deleted Table 1 since it is already discussed in the AMOS memo for the 2014 pro posal