Federal

Federal Regulation of Residential Wood-Burning

Burning wood is not regulated at the federal level.  The federal government’s role in residential wood-burning is limited to attempting to control air emissions through manufacturing standards for certain, but not all, residential wood heaters.  Specifically, federal regulations promulgated by the United States Environmental Protection Agency (“EPA”), pursuant to the Clean Air Act, sets manufacturing standards of new residential wood heaters, including allowable emissions.  EPA promulgated new source performance standards (“NSPS”) in 1988 for adjustable burn-rate wood stoves.[i]  The NSPS limit particulate matter (“PM”) emissions from these wood stoves due to their ability to contribute significantly to air pollution endangering public health.[ii]  These regulations affect only adjustable burn-rate wood stoves, not other types of residential wood heaters such as Outdoor Wood Boilers (also known as hydronic heaters).

The EPA has proposed revisions to these NSPS.[iii]  The proposed revisions phase-in emission limits to control air pollution from adjustable burn-rate wood stoves.[iv]  The revisions for the first time also add NSPS for pellet stoves, OWBs, forced-air furnaces, masonry wood heaters, and single burn-rate wood stoves.[v]  The proposed rule does not affect existing wood stoves, indoor or outdoor fireplaces, pizza ovens, barbecues, chimineas, or existing heaters fueled solely by oil, gas or coal.  Because the rule is still in its proposal phase, the 1988 regulations remain in force until a final rule is issued.


[i] 40 CFR §§ 60.530-60.539b.

[ii] 53 Fed. Reg. 5860 (1998).

[iii] 79 Fed. Reg. 6330.

[iv] Id.

[v] Id. 

State and Federal Laws Applicable to Industrial, Commercial, and Institutional Boilers

I.          Current Federal Law Implementation

In March 2011, with later revisions in early 2013, the United States Environmental Protection Agency (“EPA”) finalized national emissions standards for hazardous air pollutants (“NESHAPs”) that reduce emissions of air toxics from existing and new industrial, commercial, and institutional boilers (“ICIs”).[1]  The Clean Air Act (“CAA”) requires EPA to develop rules reducing specific hazardous air pollutants (“HAPs”), and ICIs are listed in the CAA as source categories subject to either maximum achievable control technology (“MACT”) or generally available control technology (“GACT”) regulation for specific air toxics.[2]  Different regulations are in place depending on the facility’s actual emissions or potential to emit.[3]  An ICI boiler is considered to be a “major” source of air pollution if it emits or has the potential to emit at least 10 tons per year (“tpy”) of any single air toxic or at least 25 tpy of any combination of air toxics, and these sources are subject to MACT.[4]  An ICI boiler is considered to be an “area” source of air pollution if it emits or has the potential to emit less than 10 tpy of any single air toxic or at least 25 tpy of any combination of air toxics, and these sources can be subject to either MACT or GACT.[5]  The HAPs reduced by these rules include, but are not limited to, mercury, metals, and organic air toxics including dioxins.[6]

Pursuant to the CAA’s federalism approach to regulating air pollution, states are responsible for implementing the CAA and regulations stemming from it within their borders.[7]  In the Commonwealth of Pennsylvania, the Pennsylvania Department of Environmental Protection (“PADEP”) is responsible for ensuring that the air quality permits issued to ICIs adequately incorporate EPA’s air toxic emissions standards for these sources.[8]

  1. Area Boilers – Current Applicable Regulations

The EPA regulations for area source boilers separate these boilers into two categories, large and small.[9]  Large boilers have a heat input capacity equal to or greater than 10 million British thermal units per hour (Btu per hr).[10]  Small boilers have a heat input capacity less than 10 million Btu per hour.[11]  The regulations establish standards to limit mercury emissions, particulate matter (“PM”) emissions (surrogate for non-mercury metals), and carbon monoxide (“CO”) (surrogate for organic air toxics). For new boilers, the final rule requires that large biomass boilers must meet emission limits for PM and that small boilers must only perform a boiler tune-up every two years.  For existing boilers, the final rule requires that biomass boilers are not required to meet emission limits but are instead required to meet a work practice standard or management practice by performing a boiler tune-up every two years.  Existing large biomass boilers are also required to conduct an energy assessment aimed at identifying cost-effective energy conservation measures.[12]

  1. Major Boilers – Current Applicable Regulations

The EPA regulations for major sources boilers define fifteen (15) different subcategories of boilers and process heaters based on the units’ designs, and each subcategory has specific requirements.[13]  For all new and existing units with a heat input capacity less than 10 million Btu per hour, the regulation establishes a work practice standard of performing a tune-up for each unit once every two years rather than a numeric emission limit.  This is also the case for every new and existing “limited use” boilers, which are those operated less than 10 percent of the year as emergency and backup boilers.  Generally speaking, for those new and existing major biomass boilers that have heat input capacity greater than 10 million Btu per hour and are not “limited use” boilers, the regulation establishes numeric emission limits for PM (surrogate for non-mercury metals).  These limits are different for each biomass fuel subcategory.  The rule also requires monitoring to assure compliance with emission limits and to assure that pollution controls are operating within appropriate parameters.  Additionally, boilers larger than 10 million Btu/hr must monitor oxygen as a measure of good combustion.  Finally, existing major source facilities are required to conduct a one-time energy assessment to identify cost-effective energy conservation measures.[14]

II.        Opportunities to Address ICIs

The Clean Air Council monitors on PA DEP permitting action relating to ICIs that use biomass as fuel. Where it deems necessary, the Council comments on these permitting actions in hopes to ensure that PA DEP issued permits are up-to-date and contain the correct requirements and emissions controls set forth in EPA’s regulations.

The Council is also working with other environmental organizations to address the stringency of EPA’s regulations.  Specifically, the Council and other organizations petitioned the United States Court of Appeals, District of Columbia Circuit to review the rules addressing both area and major ICI boilers.


[1] 78 Fed. Reg. 7488 (2013); 78 Fed. Reg. 7138 (2013); 76 Fed. Reg. 15608 (2011); 76 Fed. Reg. 15554 (2011).

[2] 42 U.S.C. § 7412.

[3] 78 Fed. Reg. 7488 (2013) (area boilers); 76 Fed. Reg. 15554 (2011) (area boilers); 78 Fed. Reg. 7138 (2013) (major boilers); 76 Fed. Reg. 15608 (2013) (major boilers).

[4] 42 U.S.C. § 7412(a)(1), (2).

[5] § 7412(a)(2), (d)(5).

[6] 78 Fed. Reg. 7488 (2013)

[7] 42 U.S.C. §§ 7410(a), 7412(l).

[8] 35 P.S. §§ 4004(1), 4006.6.

[9] 76 Fed. Reg. at 15559-63 (2011).

[10] Id.

[11] Id.

[12] Id.

[13] 76 Fed. Reg. 15608.

[14] Id.

Legal Disclaimer

The materials available at this web site are for informational purposes only and not for the purpose of providing legal advice. You should contact your attorney to obtain advice with respect to any particular issue or problem. Use of and access to this Web site or any of the e-mail links contained within the site do not create an attorney-client relationship between Clean Air Council and the user or browser.

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