FACT SHEET

Proposed Amendments to Air Toxics Standards for Lime Manufacturing Plants

ACTION

•	On December 20, 2022, the U.S. Environmental Protection Agency (EPA) proposed
amendments to the National Emission Standards for Hazardous Air Pollutants (NESHAP)
for Lime Manufacturing Plants.

•	The amendments are EPA's response to one remand issued by the D.C. Circuit Court in
Louisiana Environmental Action Network v. EPA.

•	This action proposes maximum achievable control technology (MACT) standards for four
pollutants: hydrogen chloride (HCI), mercury, total hydrocarbon (THC) as a surrogate for
organic HAP (o-HAP), and dioxin/furans (D/F).

•	These amendments will protect air quality and public health by reducing emissions of
HAPs such as HCI, mercury, THC, and D/F.

•	EPA estimates the proposed amendments would have a total annual cost to industry of
approximately $32 million per year.

•	The proposed action is estimated to reduce total HAP emissions from the lime
manufacturing source category by approximately 1,720 tons per year.

BACKGROUND

•	Lime manufacturing Plants in this source category include facilities engaged in the
manufacture of lime product (calcium oxide, calcium oxide with magnesium oxide, or
dead burned dolomite) by calcination of limestone, dolomite, shells, or other calcareous
substances.

•	In 2004, EPA published MACT standards for particulate matter (PM) as a surrogate for
metal hazardous air pollutants (HAP).

•	In 2020, EPA finalized the results of a residual risk and technology review (RTR), where
EPA found that the risks associated with air emissions from lime manufacturing were
acceptable and that the current NESHAP provides an ample margin of safety to protect
public health.

•	In Louisiana Environmental Action Network v. EPA, the D.C. Court held that EPA has an
obligation to address unregulated emissions from a source category when the agency
conducts an 8-year technology review required by the Clean Air Act (LEAN Decision).

•	As a result of emissions data collected for the 2020 RTR, EPA identified 4 previously
unregulated pollutants: HCI, mercury, THC, and D/F, and is proposing to set MACT
standards for these pollutants.

•	The MACT floor for existing sources is calculated based on the average performance of
the best-performing units in each category or subcategory, and the MACT floor for new

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sources is based on the single best-performing source, both with a consideration of that
source's variability.

NEW MACT STANDARDS

•	The amendments proposed set MACT standards for HCI, mercury, THC, and D/F,
pursuant to the Clean Air Act (CAA), sections 112(d)(2) and (3).

•	The MACT standards for existing sources is calculated based on the average
performance of the best-performing units in each category or subcategory, and the
MACT standards for new sources is based on the single best-performing source.

•	We are proposing, based on the proposed MACT standards for new and existing sources
in the lime manufacturing source category, that new sources demonstrate initial
compliance within 180 days after start-up, and existing sources demonstrate initial
compliance within 3 years after the promulgation of the final rule.

FOR MORE INFORMATION

•	Interested parties can download a copy of the rule notice from EPA's web site at the
following address: https://www.epa.eov/stationairv-soyirces-aiir-pollllytion/lliirne-

II :turing~plants~national~emission~standards~hazardous

•	This final action and other background information are also available electronically at
https://www.regulations.gov/. EPA's electronic public docket and comment system.

•	For further technical information about the rule, contact Brian Storey, EPA's Office of Air
Quality Planning and Standards, Sector Policies and Programs Division, at (919) 541-1103
or storey.brian@epa.gov.

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