Fluoride Action Network

Hydrogen Fluoride from Cement Kilns – EPA’s proposal for air emission standards

Source: Federal Register | November 4th, 2017 | A Proposed Rule by the Environmental Protection Agency
Industry type: Cement Kilns

Note from FAN: The following are excerpts from a lengthy proposed Rule first published on September 21, 2017. The comment period has been extended to November 21, 2017.

The Environmental Protection Agency (EPA) is proposing amendments to the National Emission Standards for Hazardous Air Pollutants (NESHAP) From the Portland Cement Manufacturing Industry to address the results of the residual risk and technology review (RTR) the EPA is required to conduct in accordance with section 112 of the Clean Air Act (CAA). We found risks due to emissions of air toxics to be acceptable from this source category with an ample margin of safety, and we identified no new cost-effective controls under the technology review to achieve further emissions reductions. Therefore, we are proposing no revisions to the numerical emission limits based on these analyses. However, the EPA is proposing amendments to correct and clarify rule requirements and provisions. While the proposed amendments would not result in reductions in emissions of hazardous air pollutants (HAP), this action, if finalized, would result in improved monitoring, compliance, and implementation of the rule…

Comments. Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2016-0442, at http://www.regulations.gov. Follow the online instructions for submitting comments…

The EPA has established a docket for this rulemaking under Docket ID No. EPA-HQ-OAR-2016-0442

II. Background

A. What is the Statutory Authority for this Action?

Section 112 of the CAA establishes a two-stage regulatory process to address emissions of HAP from stationary sources. In the first stage, after the EPA has identified categories of sources emitting one or more of the HAP listed in CAA section 112(b), CAA section 112(d) requires us to promulgate technology-based NESHAP for those sources. “Major sources” are those that emit or have the potential to emit 10 tons per year (tpy) or more of a single HAP or 25 tpy or more of any combination of HAP. For major sources, the technology-based NESHAP must reflect the maximum degree of emission reductions of HAP achievable (after considering cost, energy requirements, and non-air quality health and environmental impacts) and are commonly referred to as maximum achievable control technology (MACT) standards…

b. Environmental HAP

The EPA focuses on eight HAP, which we refer to as “environmental HAP,” in its screening analysis: Six PB-HAP and two acid gases. The six PB-HAP are cadmium compounds, D/F, arsenic compounds, POM, mercury compounds (both inorganic mercury and methyl mercury), and lead compounds. The two acid gases are HCl and hydrogen fluoride (HF). The rationale for including these eight HAP in the environmental risk screening analysis is presented below…

The main source of air toxics emissions from a Portland cement plant is the kiln. Emissions originate from the burning of fuels and heating of feed materials… [Note from FAN: Cement kilns burn municipal and hazardous waste for cheap fuel.]

Due to their well-documented potential to cause direct damage to terrestrial plants, we include two acid gases, HCl and HF, in the environmental screening analysis. According to the 2005 NEI, HCl and HF account for about 99 percent (on a mass basis) of the total acid gas HAP emitted by stationary sources in the U.S. In addition to the potential to cause direct damage to plants, high concentrations of HF in the air have been linked to fluorosis in livestock. Air concentrations of these HAP are already calculated as part of the human multipathway exposure and risk screening analysis using the HEM3-AERMOD air dispersion model, and we are able to use the air dispersion modeling results to estimate the potential for an adverse environmental effect…

For HF, the EPA identified chronic benchmark concentrations for plants and evaluated chronic exposures to plants in the screening analysis. High concentrations of HF in the air have also been linked to fluorosis in livestock. However, the HF concentrations at which fluorosis in livestock occur are higher than those at which plant damage begins. Therefore, the benchmarks for plants are protective of both plants and livestock…

The EPA evaluates the following eight HAP in the environmental risk screening assessment: cadmium compounds, D/F, arsenic compounds, POM, mercury compounds (both inorganic mercury and methyl mercury), lead compounds, HCl, and HF, where applicable. These eight HAP represent pollutants that can cause adverse impacts for plants and animals either through direct exposure to HAP in the air or through exposure to HAP that is deposited from the air onto soils and surface waters. These eight HAP also represent those HAP for which we can conduct a meaningful environmental risk screening assessment. For other HAP not included in our screening assessment, the model has not been parameterized such that it can be used for that purpose. In some cases, depending on the HAP, we may not have appropriate multipathway models that allow us to predict the concentration of that pollutant. The EPA acknowledges that other HAP beyond the eight HAP that we are evaluating may have the potential to cause adverse environmental effects and, therefore, the EPA may evaluate other relevant HAP in the future, as modeling science and resources allow…

… in order to characterize non-cancer chronic effects, and in response to key recommendations from the SAB, the EPA selects dose-response values that reflect the best available science for all HAP included in RTR risk assessments.[7] More specifically, for a given HAP, the EPA examines the availability of inhalation reference values from the sources included in our tiered approach (e.g., IRIS first, ATSDR second, CalEPA third) and determines which inhalation reference value represents the best available science. Thus, as new inhalation reference values become available, the EPA will typically evaluate them and determine whether they should be given preference over those currently being used in RTR risk assessments.

The EPA also evaluated screening estimates of acute exposures and risks for each of the HAP (for which appropriate acute dose-response values are available) at the point of highest potential off-site exposure for each facility. To do this, the EPA estimated the risks when both the peak hourly emissions rate and worst-case dispersion conditions occur. We also assume that a person is located at the point of highest impact during that same time. In accordance with our mandate in section 112 of the CAA, we use the point of highest off-site exposure to assess the potential risk to the maximally exposed individual. The acute HQ is the estimated acute exposure divided by the acute dose-response value. In each case, the EPA calculated acute HQ values using best available, short-term dose-response values. These acute dose-response values, which are described below, include the acute REL, acute exposure guideline levels (AEGL) and Emergency Response Planning Guidelines (ERPG) for 1-hour exposure durations. As discussed below, we used conservative assumptions for emissions rates, meteorology, and exposure location.

As described in the CalEPA’s Air Toxics Hot Spots Program Risk Start Printed Page 44263Assessment Guidelines, Part I, The Determination of Acute Reference Exposure Levels for Airborne Toxicants, an acute REL value (http://oehha.ca.gov/?air/?general-info/?oehha-acute-8-hour-and-chronic-reference-exposure-level-rel-summary) is defined as “the concentration level at or below which no adverse health effects are anticipated for a specified exposure duration.” Id. at page 2. Acute REL values are based on the most sensitive, relevant, adverse health effect reported in the peer-reviewed medical and toxicological literature. Acute REL values are designed to protect the most sensitive individuals in the population through the inclusion of margins of safety. Because margins of safety are incorporated to address data gaps and uncertainties, exceeding the REL does not automatically indicate an adverse health impact…

As described in Standing Operating Procedures (SOP) of the National Advisory Committee on Acute Exposure Guideline Levels for Hazardous Chemicals (https://www.epa.gov/?sites/?production/?files/?2015-09/?documents/?sop_?final_?standing_?operating_?procedures_?2001.pdf),[8] “the NRC’s previous name for acute exposure levels—community emergency exposure levels—was replaced by the term AEGL to reflect the broad application of these values to planning, response, and prevention in the community, the workplace, transportation, the military, and the remediation of Superfund sites.” Id. at 2. This document also states that AEGL values “represent threshold exposure limits for the general public and are applicable to emergency exposures ranging from 10 minutes to eight hours.” Id. at 2…

The AEGL-1 value is then specifically defined as “the airborne concentration (expressed as ppm (parts per million) or mg/m3 (milligrams per cubic meter)) of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic nonsensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure.” Id. at 3. The document also notes that, “Airborne concentrations below AEGL-1 represent exposure levels that can produce mild and progressively increasing but transient and nondisabling odor, taste, and sensory irritation or certain asymptomatic, nonsensory effects.” Id. Similarly, the document defines AEGL-2 values as “the airborne concentration (expressed as parts per million or milligrams per cubic meter) of a substance above which it is predicted that the general population, including susceptible individuals, could experience irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape.” Id...

Note From FAN:

The above is a much-abbreviated excerpt of this Proposed Rule, which provides a fascinating discussion of various pollution controls, efforts to capture mercury and a discussion of many individual cement kilns in different states. It also provides further discussion on various models and analysis that examine the potential for significant human health risks, CEMS (Continuous Emission Monitoring Systems), and more.

*This proposed Rule is lengthy. To read the full proposal go to https://www.federalregister.gov/documents/2017/09/21/2017-19448/national-emission-standards-for-hazardous-air-pollutants-from-the-portland-cement-manufacturing