After nearly two decades of regulatory uncertainty, EPA has finalized amendments to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for the Plywood and Composite Wood Products (PCWP) source category, which is 40 CFR Part 63, Subpart DDDD. Published in the Federal Register on July 6, 2026, the final rule brings 219 wood products facilities under new or expanded emission controls for the first time since the original 2004 rule was partially vacated by federal courts in 2007. Existing facilities have until July 6, 2029, to achieve full compliance.
The rule resolves a long-running rulemaking saga. In 2007, the U.S. Court of Appeals for the D.C. Circuit vacated the PCWP NESHAP provisions that had created a low-risk subcategory, effectively leaving hundreds of facilities operating with no maximum achievable control technology (MACT) obligations for nearly 20 years. This final rule closes that gap and adds entirely new pollutant categories that have never been regulated at these facilities. For wood products manufacturers, the compliance clock is now running.
Who Is Affected?
The rule applies to PCWP manufacturing facilities that are a major source of hazardous air pollutants (HAP), which is defined as any facility that emits 10 tons per year (tpy) or more of any single HAP, or 25 tpy or more of total HAPs. EPA estimates that 219 facilities fall within scope:
- 93 PCWP facilities including manufacturers of plywood, particleboard, oriented strand board (OSB), medium density fiberboard (MDF), hardboard, fiberboard, laminated veneer lumber (LVL), laminated strand lumber (LSL), wood I-joists, and glue-laminated beams
- 126 kiln-dried lumber facilities including standalone and integrated dry lumber operations
Facilities that previously believed they were exempt under the vacated 2004 subcategory determinations should pay particular attention as those “no-control” MACT determinations no longer provide protection.
What’s New: Standards by Process Unit
Direct-Fired Dryers (PCWP Facilities)
Direct-fired dryers are used across plywood, OSB, particleboard, MDF, and fiberboard production are among the most affected emission sources in the final rule. They are now subject to numerical emission limits for two categories of pollutants:
Total HAP Standards: Total HAP standard includes formaldehyde, methanol, phenol, acetaldehyde, acrolein, and propionaldehyde. Direct-fired dryers and other process units with previously vacated “no-control” MACT determinations are now subject to total HAP emission limits for the first time. These limits will require initial and ongoing performance (stack) testing to demonstrate compliance.
Newly Regulated Combustion HAP: EPA is establishing standards for pollutants emitted from combustion in direct-fired dryers that have never been regulated under the PCWP NESHAP, including non-mercury HAP metals, mercury (Hg), hydrogen chloride (HCl), polycyclic aromatic hydrocarbons (PAH). EPA is also establishing work practice standards for dioxin/furan (D/F). Many facilities have never monitored these pollutants, meaning new stack testing programs, emission inventories, and monitoring protocols will need to be built from the ground up.
Compliance will also require facilities to establish operating parameter limits following initial performance testing and implement continuous parametric monitoring, recordkeeping, and reporting all before the July 2029 compliance date.
Lumber Kilns
The final rule takes a distinct approach to lumber kilns. Rather than imposing numerical emission limits, which EPA acknowledged are not practically feasible to measure at kiln stacks, the agency is establishing work practice standards for organic HAP, combustion-related HAP, and VOC emissions.
These work practice standards include:
- Developing an operation and maintenance (O&M) plan for all kilns
- Annual burner tune-ups for direct-fired kilns
- Operating restrictions on temperature and moisture content or developing a site-specific plan to prevent over-drying
While work practice standards may sound less burdensome than numerical limits, the requirements carry real compliance obligations. Facilities must develop and implement formal programs, maintain records demonstrating program execution, and demonstrate compliance. The 126 kiln-dried lumber facilities subject to these new work practice standards will need to develop a PCWP compliance program before the July 2029 compliance date.
MDI Resin and Coating Processes
Facilities using methylene diphenyl diisocyanate (MDI) resins or coatings that are commonly found in OSB, engineered lumber, and I-joist manufacturing are subject to new emission standards specifically targeting MDI. These standards apply to pressing operations where MDI is used as a binder or coating agent. Affected facilities will need to evaluate their MDI usage, quantify potential HAP emissions, and implement work practices or engineering controls to achieve compliance.
Previously Unregulated “No-Control” Sources
Perhaps the most significant impact of the final rule is felt by facilities that relied on the vacated 2004 subcategory to avoid MACT compliance entirely. These process units include various resonated material handling (RMH) process units, atmospheric refiners, stand-alone digesters, fiber washers, fiberboard mat dryers at existing sources, hardboard press predryers at existing sources, and log vats.
For these sources, every compliance obligation is new: applicability determination, HAP emission inventory, performance testing, monitoring plan development, permit modification, and recordkeeping systems. These facilities face the largest compliance gap with the shortest runway to close it.
Air Permitting Implications
The final rule will trigger permit modification obligations for virtually every affected Title V facility. New applicable requirements including emission limits, work practice standards, monitoring and testing requirements, and compliance notification deadlines to be incorporated into facility operating permits. Facilities not currently operating as Title V major sources should also reassess their HAP potential to emit emissions in light of the new requirements.
What Facilities Should Do Now
With a compliance deadline of July 6, 2029, three years may seem sufficient, but the scope of work is substantial. Facilities should begin immediately:
- Applicability Determination: Confirm whether your facility is a major HAP source and which process units are subject to the rule, including any previously vacated subcategory sources
- HAP Emissions Inventory: Quantify actual and potential emissions for all regulated pollutants, including newly regulated combustion HAP (metals, Hg, HCl, PAH, D/F) that may never have been characterized
- Compliance Gap Assessment: Compare current operations and emission controls against the new emission limits and work practice standards
- Performance Test Planning: Develop stack testing protocol and schedule initial stack tests for dryers and other affected emission units well in advance of the July 2029 deadline
- Title V Permit Modifications: Initiate permit modification to incorporate new applicable requirements
How Trinity Can Help
Trinity Consultants (Trinity) has deep experience supporting plywood, OSB, MDF, particleboard, hardboard, and kiln-dried lumber facilities with PCWP NESHAP compliance. Through active participation National Council for Air and Stream Improvement, Inc. (NCASI) and longstanding history working with wood products manufacturers nationwide, our team has followed the PCWP NESHAP rulemaking since the 2007 vacatur and is ready to help facilities respond quickly and effectively.
Trinity’s Capabilities Include:
NESHAP/MACT Compliance Support
- Applicability determinations and regulatory interpretations under PCWP MACT
- Compliance gap assessments benchmarked against final emission limits and work practice standards
- Development of MACT compliance programs for previously unregulated sources
- MDI process evaluations and work practice program development
- Lumber kiln maintenance plan and burner tune-up program development
Stack Testing and Emissions Monitoring
- Performance test planning and management for total HAP, HAP metals, Hg, HCl, PAH, and D/F
- Development of monitoring plans and operating parameter limits for dryers and other emission units
- Emissions inventory development for newly regulated combustion HAP
- CEMS and parametric monitoring program support
Air Quality Permitting
- Title V permit modification support to incorporate new PCWP NESHAP requirements
- Minor and major source permitting for process modifications or control device installations
- NSR/PSD applicability analyses for control technology additions
- State agency coordination and permit negotiation support
Auditing and Verification
- Pre-compliance audits to identify gaps and prioritize corrective actions before the July 2029 deadline
- Multi-media compliance audits for facilities managing simultaneous regulatory obligations
- Recordkeeping and reporting system review and development
Control Technology Evaluation
- Evaluation of add-on emission control options (regenerative thermal oxidizers, biofilters, wet scrubbers) for dryer emission limits
- Cost-effectiveness analyses to identify the most practical compliance pathway
- Vendor coordination and engineering support for control device selection and installation
The Clock Is Running — Start Now
The final PCWP NESHAP rule is the most significant air regulatory development for the wood products sector in more than 20 years. With 219 facilities on the compliance clock, demand for specialized PCWP expertise will be high. Trinity’s team is available now to help facilities assess their obligations, design a compliance roadmap, and begin the testing and permitting work required to meet the 2029 deadline.
If you would like to learn more about how Trinity can assist your facility with PCWP NESHAP compliance, please email Jesslynn Hale at [email protected] or contact via phone at 501.225.6400.
