U.S. EPA Has Finalized Updates to the Wood Products NESHAP

Author: Amy Marshall

The U.S. Environmental Protection Agency (U.S. EPA) published significant amendments to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Plywood and Composite Wood Products (PCWP) on July 6, 2026. The original NESHAP focused primarily on organic hazardous air pollutant (HAP) emissions from certain types of wood products’ dryers and presses. These amendments address the 2007 partial remand and vacatur of portions of the original 2004 PCWP NESHAP (U.S. EPA had not set any standards for several types of emissions units that had no HAP controls) and a petition for reconsideration that U.S. EPA received on the 2020 Risk and Technology Review (RTR) of the NESHAP. In summary, to close out several years of work on this rule, U.S. EPA has set emissions standards for several types of process units that are part of the affected source but did not have any requirements and set emissions standards for several new pollutants for some sources already regulated. This article discusses major amendments to the rule.

Work Practice Standards for Lumber Kilns

Lumber kilns are part of the affected source under the PCWP NESHAP but were not previously subject to any standards. U.S. EPA has finalized standards for lumber kilns that include the following elements:

• An operation and maintenance plan for all types of kilns,
• Annual burner tune-ups and bypass stack monitoring for direct-fired kilns,
• Work practices to limit over-drying of lumber using temperature and moisture.

To limit over-drying of lumber, facilities will choose from three options that involve continuous monitoring: (1) limiting the kiln to operation at low drying temperatures, (2) limiting the kiln to operation at higher temperatures while also monitoring the moisture content of the wood being dried, or (3) establishing a site-specific plan that contains both temperature and lumber moisture content limitations. The site-specific plan will be submitted to the delegated agency for approval and incorporated into the facility’s Title V permit if option 3 is selected.

Additional Standards for Direct-Fired Dryers

U.S. EPA has added work practice standards for all direct-fired dryers and numeric standards for emissions of filterable particulate matter (PM), mercury, hydrochloric acid (HCl), and polycyclic aromatic hydrocarbons (PAH) from biomass direct-fired dryers. One type of biomass direct-fired dryer (i.e., green rotary) also has a dioxin/furan limit. U.S. EPA defines a natural gas direct-fired dryer as one where greater than 90 percent of the direct heat results from gas combustion and a biomass direct-fired dryer as one where at least 10 percent of the direct heat comes from biomass combustion.

The work practice standards for direct-fired dryers include annual tune-ups (similar to the Industrial Boiler NESHAP) to ensure good combustion and monitoring of bypass stack use during startup or shutdown. The numeric standards for biomass direct-fired dryers are subcategorized according to dryer type (rotary strand, green rotary, dry rotary, tube, and softwood veneer) and compliance must be demonstrated via continuous monitoring and stack testing every five years. Two options are provided for compliance with the new numeric standards: production based or concentration based.

Standards for Resinated Material Handling Process Units

Resinated Material Handling (RMH) process units are resin tanks, softwood and hardwood plywood presses, engineered wood products presses and curing chambers, blenders, formers, finishing saws, finishing sanders, panel trim chippers, reconstituted wood products board coolers (at existing affected sources), hardboard humidifiers, and wastewater treatment operations. These process units handle resin or resinated wood material downstream of the point in the PCWP process where resin is applied. U.S. EPA finalized work practice standards for these RMH process units because they do not currently have any requirements in the rule and are generally fugitive sources of organic HAP. The proposed standards are:

• Use only a non-HAP resin OR use a resin with a maximum true vapor pressure less than or equal to 5.2 kPa (0.75 psia) for resins stored in tanks >40,000 gallons and 13.1kPa (1.9 psia) for resins stored in tanks <40,000 gallons OR use a combination of resins meeting the first two options. A non-HAP resin is one that contains less than 0.1% by mass of formaldehyde and less than 1.0% by mass each of phenol, methanol, and methylene diphenyl diisocyanate (MDI).
• Process wood material that was purchased pre-dried to a moisture content of no more than 30 weight percent, dry basis or that has been dried in a dryer located at the PCWP facility. This requirement does not apply to wet formers or on-site wastewater treatment operations.

No standards for wastewater treatment operations were finalized.

Other New Requirements

Other requirements U.S. EPA added are:

• Work practice standards for log vats,
• Numeric standards for process units with MDI emissions,
• Numeric standards for atmospheric refiners,
• Work practice standards for stand-alone digesters and fiber washers,
• Numeric standards for fiberboard mat dryers and press predryers at existing sources,
• Standards for mixed process streams,
• Repeat testing and parameter monitoring requirements for the added numeric standards.

U.S. EPA also removed the emissions averaging provisions, updated the electronic reporting template, and made various corrections/clarifications to rule text.

The Path Forward

New facilities (those constructed or reconstructed after the May 18, 2023 proposal date) must comply with the new requirements upon the effective date of the rule (July 6, 2026) but have 180 days to conduct any required performance testing. Existing facilities have three years to comply with the new requirements, although any facility with a lumber kiln that chooses the site-specific work practice option will need to prepare and submit the plan within 18 months and any facility with requirements for “mixed process streams” has 30 days to submit a notification of compliance status (NOCS).

The new standards may result in the need for process and monitoring system changes, so it will be important to perform a gap analysis as early as possible to determine the need for any modifications to comply with the new standards. ALL4 can help you review and determine applicability of new requirements, identify gaps, prepare a compliance strategy, provide training, and implement compliance requirements. Feel free to reach out to Amy Marshall at amarshall@all4inc.com if you need assistance.