August 28, 2026
Chris Hoagland, Director of Air & Radiation Administration
Maryland Department of the Environment
1800 Washington Blvd.
Baltimore, Maryland 21230
Chris.hoagland@maryland.gov
Suna Yi Sariscak, Program Manager
Air Quality Permits Program
Air & Radiation Administration
Maryland Department of the Environment
1800 Washington Blvd.
Baltimore, Maryland 21230
Suna.sariscak@maryland.gov
Shannon Heafey, Public Participation Coordinator
Air Quality Permit Program
Air & Radiation Administration
Maryland Department of the Environment
1800 Washington Blvd.
Baltimore, Maryland 21230
Shannon.heafey@maryland.gov
Subject: W.R. Grace Plastic Waste Pyrolysis Incinerator in Columbia, Maryland
Dear Director Hoagland, Program Manager Sariscak, and Coordinator Heafey,
We are writing to share our concerns about the proposed permit for the pyrolysis plasticsburning incinerator at the WR Grace facility in Columbia. The Maryland Department of the Environment (MDE) describes this facility as “a research-scale pilot plant including small, R&D-scale reactors, chillers, separators, feeders, and samplers with an exhaust gas stream, cleaned by an electric, flameless thermal oxidizer.” We have learned that MDE is now on the verge of granting an “extension” to existing construction- and operating permits – making them permanent -- without even offering the public a chance to weigh in. No public hearing, no
comment period, nothing.
On behalf of our 149 active members in Columbia, 5,252 active members in Maryland, and 1.6 million members nationwide, we urge you to reverse course and to protect the children and families of Cedar Creek and Columbia Maryland, and beyond.
Pyrolysis incinerators are dual-chamber combustors in which plastic waste is heated, transforming it into harmful air pollution, hazardous waste ash, synthetic gas, and toxic pyrolysis oils. Most of the oils are used to make heavily contaminated fuels. Burning plastic in pyrolysis combustors releases health-harming air pollutants such as dioxins, benzene, and heavy metals.
Clean Air Act section 129 limits the allowable emissions from pyrolysis incinerators – but W.R. Grace seeks to circumvent the law
The Clean Air Act requires strict emission limits -- and monitoring, reporting, and permitting requirements -- for only two types of sources of hazardous air pollutants: “incinerators” and “major sources.” Many pyrolysis incineration facilities (such as the one at the W.R. Grace facility) would not be large enough to be called “major sources” of hazardous air pollutants because the quantities of hazardous air pollutants they release do not reach the Clean Air Act threshold amounts (10 tons per year of any individual hazardous air pollutant or 25 tons of combined HAPs).
The drafters of the Clean Air Act Amendments of 1990 did not want any incinerators, small or large, to escape regulation. Thus, they included a special section in the Clean Air Act solely for incinerators. They did this for good reason: burning solid waste releases potent carcinogens. Many of the pollutants that incinerators emit, including dioxins, cadmium, and lead, are toxic in tiny quantities – mere fractions of a gram can be enough to trigger life-altering effects. They also persist in the environment and accumulate in food sources, human bodies, and even mother’s milk.
Thus, even though the amount of these pollutants may not meet the “major source” 10-ton/25-ton threshold requirements for Maximum Achievable Control Technology (MACT) regulation under Clean Air Act section 112, the quantities of the super-toxic emissions released by incinerators are more than ample to make people gravely ill. The highly toxic pollutants released by solid waste incinerators cause cancer, asthma, and ADHD, disrupt reproduction, and make our endocrine systems go haywire. The dangers are most acute for the unborn and for infants and children, whose developing bodies are uniquely vulnerable to pollution exposures.
The only way to regulate the extremely dangerous emissions from the pyrolysis incinerators that don’t reach the 10-/ 25- ton hazardous air pollution thresholds is via the Clean Air Act provisions that Congress enacted specifically to address this pollution: Section 129 of the Act. These provisions specify numerical emissions limits for particulate matter, opacity, sulfur dioxide, hydrogen chloride, nitrogen oxides, carbon monoxide, lead, cadmium, mercury, dioxins and dibenzofurans. The Act defines “solid waste incineration unit” as “a distinct operating unit of any facility which combusts any solid waste material from commercial or industrial establishments or the general public.” [Emphasis added.]
Because they “combust[ ] solid waste material from commercial or industrial establishments or the general public,” pyrolysis units are subject to the pollution control standards of Clean Air Act section 129. EPA has regulated pyrolysis incinerators alongside other incinerators for 30 years. In its very first standards promulgated under the Clean Air Act, the agency specified that “Municipal solid waste combustion includes the direct combustion of MSW or the combustion of MSW gases from pyrolysis or gasification.”
The Clean Air Act defines “solid waste incineration unit” as “any facility which combusts any solid waste material from commercial or industrial establishments or the general public.” [Emphasis added.] EPA (and MDE) are required by law to regulate these incinerators according to Clean Air Act section 129.
The proposed “research exemption” is unlawful
W.R. Grace has been trying to skirt the Clean Air Act incinerator rules using loopholes and false assertions. In particular, the company has been suggesting that it qualifies for a research exemption. There is no such exemption.
The Clean Air Act section 129 implementing regulations do offer a far more narrow exemption for Laboratory Analysis Units, but the large scale at which W.R. Grace is operating does not qualify. The regulations state,
(j) Laboratory Analysis Units. The unit is excluded if it burns samples of materials only
for the purpose of chemical or physical analysis
W.R. Grace’s Permit to Construct granted by MDE in June, 2025 (permit 027-0013-0088) incorrectly suggests on p. 7 that the Other Solid Waste Incinerator Rules (OSWI, implementing section 129 of the Clean Air Act) do not apply because “the new pilot plant shall be used for the sole purpose of research.”
This is a fundamental misinterpretation of the rules. There is no research exemption under section 129. MDE has given W.R. Grace a permit to burn 4,000 kg of plastic waste per year, which is the same as 8,818.49 lbs, i.e. 24.16 lbs per day. That is vastly much more plastic waste than what would be used for “laboratory analysis” under the regulations. 8,818 lbs does not constitute mere “samples” of material for the purpose of “chemical or physical analysis.”
Burning multiple pounds per day involves a scale of operations that’s used for validation before full commercial deployment. And as such, it is completely ineligible for the “chemical or physical analysis” exemption.
Laboratory-scale analyses typically consume milligrams to grams of plastic per test. Such analyses are used, for example, to characterize the raw plastic waste feedstock and to identify its thermal degradation behavior. Those sorts of analyses take place at a micro scale. For example, in pyrolysis-gas chromatography-mass spectrometry, micrograms of plastic are thermally cracked in a specialized micro-furnace. The resulting vapors are then identified and separated, enabling researchers to evaluate how the plastic decomposes, whether it’s more like “unzipping” (e.g. polystyrene) or breaking apart at random locations (e.g., polyethylene) into a mix of gaseous and liquid hydrocarbons. Those experiments happen at the laboratory or bench scale and thus would likely be eligible for the Laboratory Analysis Unit exemption.
By contrast, the W.R. Grace pyrolysis unit is not a bench nor an experimental-sized analytical unit. If it were, it would not need a thermal oxidizer to treat the off-gases. W.R. Grace is operating a pre-commercial-scale pyrolysis incinerator.
Moreover, Clean Air Act section 129 applies to any solid waste combustion. To claim otherwise would be flatly unlawful. Section 129(a)(1) mandates regulation of all “solid waste incineration units,” and 129(g)(1) defines “solid waste incineration unit” to mean “a distinct operating unit of any facility which combusts any solid waste material from commercial or industrial establishments or the general public (including single and multiple residences, hotels, and motels).” 42 U.S.C. § 7429(a)(1), (g)(1). Section 129(g)(1) provides a short and very specific list of the facilities that combust waste but are not solid waste incinerators. This makes clear that Congress had no intention of excluding “research facilities” or “pilot-scale” operations from
the definition of “solid waste incineration unit” or from regulation as incinerators.
The D.C. Circuit has confirmed the Clean Air Act’s plain meaning in multiple decisions. In 2007, for example, in NRDC v. EPA, 489 F.3d 1250, 1256 1261 (D.C. Cir. 2007), the Court confirmed that when Congress defined solid waste incineration unit to mean “any” facility which combusts “any” solid waste material, it meant precisely that. The D.C. Circuit “interpret[ed] section 129 … to unambiguously include among the incineration units subject to its standards any facility that combusts any commercial or industrial solid waste material at all—subject to the four statutory exceptions identified above” (emphasis added). Pilot-scale research units (or any research facilities) are not among the exceptions.
In 2016, the D.C. Circuit confirmed and expanded on its holding in NRDC. U.S. Sugar Corp. v. EPA, 830 F.3d 579, 643-644 (D.C. Cir. 2016). The Court held “this argument misses the point: in light of the unambiguous statutory command to promulgate numeric standards for all solid waste incineration units, the EPA had no discretion to avoid regulating any such units—even if its choice to avoid regulating these units would have been otherwise reasonable.” The Court made clear that the Clean Air Act unambiguously requires section 129 standards for any pyrolysis incinerator that combusts any waste at all.
The W.R. Grace plastics pyrolysis incinerator poses a significant danger to people who live, work, or go to school in Columbia Maryland Plastics pyrolysis, which the chemical industry calls “advanced recycling,” is a process meant to break down or deconstruct plastic into its chemical building blocks. In practice it involves heavily polluting incinerators in which plastic waste is heated and turned into harmful air pollution, hazardous waste ash, synthetic gas, and toxic pyrolysis oils that are used to make heavily contaminated fuels.
Pyrolysis incineration generally takes place between 300- and 900- degrees C. This span of temperatures within the incinerator, combined with the reduced level of oxygen, promotes the generation of incomplete combustion products including PAHs, PCBs, formaldehyde, carbon monoxide, dioxins, and furans.
In fact, these relatively low incineration temperatures of the plastics-pyrolysis process are ideal for the production of dioxins. Dioxins are known as “the most toxic poison on earth,” and a single gram can kill tens of thousands of people. The most dangerous type of dioxin is 2,3,7,8- TCDD, which is hundreds of times more toxic than arsenic or potassium cyanide. This congener of dioxin can form in plastic pyrolysis incinerators, especially in the presence of chlorine.
Bypassing the Clean Air Act solid waste incineration rules and Title V requirements would enable W.R. Grace to circumvent section 129’s strict pollution control standards for dioxins and other harmful chemicals, as well as the monitoring and reporting requirements, thus exposing the community to these potent carcinogens.
The W.R. Grace plastics-burning incinerator is located just 70 meters from nearby homes where children and families live. Yet the Maryland Department of the Environment would allow this serial polluter to sidestep Clean Air Act rules in its operation of the plastics pyrolysis incinerator.
With this decision, MDE would effectively signal to the chemical industry that they can freely expand into residential areas across the state, and that Maryland’s air quality regulators are willing to sign off on the permits without even giving residents an opportunity to speak.
Choosing to prioritize plastics-industry profits over the health of children would set a dangerous precedent for all Marylanders. We urge you to reconsider.
Yours sincerely,
Cynthia Palmer
Senior Analyst, Petrochemicals
Moms Clean Air Force