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The National Association of Clean Air Agencies (“NACAA”) submitted February 6th comments on the U.S. Environmental Protection Agency (“EPA”) proposed:

National Emission Standards for Hazardous Air Pollutants: Miscellaneous Organic Chemical Manufacturing Residual Risk and Technology Review (“Proposal”)

The Proposal was published on December 17, 2019, in the Federal Register. See 84 Fed. Reg. 69,182.

Section 112 of the Clean Air Act requires development of the National Emission Standards for Hazardous Air Pollutants for categories of stationary sources. The first stage involves the establishment of technology-based standards. The second stage requires that EPA evaluate those standards. This evaluation determines whether the current technology-based available control technology is adequate or additional standards needed to address any remaining risks associated with hazardous air pollution emissions. This is denominated a Residual Risk and Technology Review.

NACAA initially notes its support of EPA’s interest in reducing exposures to emissions of ethylene oxide (“EtO”). It describes EtO as:

. . . carcinogenic to humans including increasing the risk of “some types of cancers, including cancers of the while blood cells . . .; and breast cancer in females.

Support is also expressed for what is described as EPA’s conclusion that “risks for this source category under the current MACT provisions are unacceptable.”

The NACAA comments address the following issues:

• Use of Integrated Risk Information System (“IRIS”) for Risk Estimates for EtO are supported
  • Deviations from the IRIS estimates are problematic
  • Concern is expressed that EPA is soliciting comment on use of updated IRIS risk value for regulatory purposes
  •  Concern is expressed that EPA discusses two possibilities for “straying” from and undermining the IRIS numbers
  • Opposes use of an uncertainty assessment in the health risk assessment to justify reducing estimated risk to acceptable levels
• Control Options
  • Recommends that controls flow logically from and be based upon the use of best risk information which is from a non-amended IRIS and latest advancements in control technologies
  • Supports EPA’s recognition of the need for more protective standards
  • Recommends the following improvements:
    • improvements to the leak detection and repair program, including lowering the definition of a leak, increasing the leak-inspection frequency, requiring leaks to be fixed within 15 days and removing the current the leak repair exemption for all pumps in EtO service;
    • enhancement of flare destruction efficiencies that go beyond the current general provision flare requirements; and
    • inclusion of the work practice provisions designed to prevent releases from pressure relief devices that directly vent to the atmosphere
• Concentrations at Census Tract Centroids
  • Concern is expressed regarding use of long-term concentrations affecting the census blocks within 50 kilometers of each facility because it dilutes the effect of sources’ emissions by estimating impact at the centroid of the census block instead of at the property line or wherever the maximum exposed individual is
  • Recommends identifying the truly maximum individual risk irrespective of its location in the census block
• Facility-Wide and Cumulative Risks
  • Recommends continuing recognition of the importance of considering the impact of emissions from all hazardous air pollutant emitting operations in a facility to determine the facility-wide risks
  • Opposes focusing solely on the source category that is the subject of the regulation
• Acute Exposure
  • Opposes use of Acute Exposure Guideline Levels or Emergency Response Planning Guidelines in residual risk assessments
  • Recommends using reference exposure levels for assessments
• Allowable Emissions
  • Recommends considering potential or allowable emissions as opposed to actual emissions in evaluating residual risk
  • States that limiting the scope of risk evaluation to actual emissions would be inconsistent with the applicability section of Part 63 rules

A copy of the comments can be downloaded here.