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Revision of New Source Performance Standards for Wood Stoves, other Residential Solid Biomass 

Combustion Devices, and Coal Stoves Under Section 111(b)(1)(B) of the Clean Air Act 

Description of the Proposals under Consideration 

• EPA intends to revise the “Standards of Performance for New Residential Wood Heaters” (codified at 40 

CFR Part 60, Subpart AAA) that were promulgated on February 26, 1988. EPA intends to tighten the 

emission limits and add standards for additional devices. EPA also intends to revise the source category 

list and develop parallel standards in new subparts for clarity and to avoid unintended consequences. 

• Like the 1988 rule, the revisions would require manufacturers of new devices to design appliances to 

meet particulate matter emission limits (principally PM2.5), have representative model lines be tested by 

independent, accredited labs, and attach EPA labels and hangtags after EPA approval. 

• Manufacturers of these devices would comply with the standards by applying Best Demonstrated 

Technology (BDT), primarily by improving combustion and heat transfer efficiency. Some manufacturers 

may chose to utilize add-on control technology such as catalysts and electrostatic precipitators to 

supplement combustion improvements. 

Types of Residential Combustion Devices for Proposals under Consideration 

• Wood Stoves 

• Pellet Stoves 

• Cook stoves, camp stoves, single-burn-rate appliances 

• Other solid biomass stoves (e.g., stoves that burn shelled corn, switchgrass, cherry pits) 

• Masonry heaters 

• Masonry fireplaces constructed on site 

• Factory-built fireplaces 

• Outdoor stoves and fireplaces (e.g., bake ovens, chimineas) 

• Outdoor hydronic heaters (aka outdoor wood boilers) 

• Indoor hydronic heaters 

• Forced-air furnaces 

• Coal stoves and heaters 

Potential Requirements of Proposals under Consideration 

• Tighten emission limits to reflect today’s BDT

• Close “loopholes”, eliminate exemptions (e.g., cook stoves)

• Add pellet stoves explicitly

• Add wood hydronic heaters and furnaces

• Revise test methods, as appropriate

• Streamline certification process and incorporate International Standards Organization (ISO) process plus 

compliance affirmation

• Improve compliance assurance and enforceability

• Regulate fireplaces

• Regulate devices fueled by other solid biomass, e.g., corn, various pelletized biomass

• Regulate coal-fired stoves and heaters to level the playing field 

• Require compliance tests on “worst” grade of each type of pellet that manufacturer specifies for use 

• Require Federal rules on pellet quality if adequate industry standards are not in place in time 
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Regulatory Flexibility Options for Small Entities 

• Since most companies are small businesses, EPA will carefully consider all options. 

• Current NSPS gave additional time for initial compliance for small volume manufacturers – we expect to

do that again. 

• Current NSPS allows manufacturers to show compliance by model lines rather than testing each source – 

we expect to continue that approach to reduce costs. 

• As EPA transitions to an ISO-accredited lab approach, we expect to give additional time to small labs that 

have experience as EPA-accredited labs. 

• For masonry heaters and site-built masonry fireplaces, we are working with the companies to consider a

2-prong NSPS that allows use of previously approved equipment standard options in lieu of testing each

new model line. 

• For single-burn appliances, we are working with the companies to consider appropriate modifications to

the test method. 

• For “traditional North American cook stoves” and “camp stoves”, we are working with the companies to 

consider definitions/equipment standards to reduce impacts. 

• For “traditional Native American bake ovens”, we are working with Tribes to develop a definition that 

will likely exclude such devices. 

• For indoor and outdoor hydronic heaters and forced air furnaces, we are working with industry to 

consider appropriate modifications to the test method to consider more flexibility in heat storage options 

and burn rate options. 

Impacts of the Proposed Actions 

• The potential benefits for reducing wood smoke emissions are very large and are expected to be much 

larger than the costs of compliance with the proposed actions. 

• Impacts of the proposed action will be more specific after additional emissions data are analyzed and 

regulatory options are clearer. 

• For perspective, the overall benefits for wood residential wood smoke emission reductions are 

approximately $500,000/ton of PM2.5 emissions reduced (actual values vary by location). 

• For example, the benefits of changing out all the old wood stoves in the U.S. to current NSPS level 

appliances are $35 billion to $86 billion per year.

• This is based principally on reductions in mortality, non-fatal heart attacks, and chronic bronchitis.

• The vast majority of the manufacturers that would be subject to this rule are small businesses with much, 

much fewer than 500 employees. 

• We estimate that ____ manufacturers of wood stoves and ____ manufacturers of pellet stoves would be 

subject to the proposed rule. (information still pending) 

• We estimate that ____ manufacturers of hydronic heaters and ____ manufacturers of factory-built 

fireplaces would be subject to the proposed rule. (information still pending) 

• EPA believes that greater emissions reductions can be achieved by operating cleaner solid biomass 

combustion devices, which can help areas of the country attain or maintain the ambient PM2.5 national 

air quality standard. 

Background 

• The development of the wood heater regulations began in the mid-1980’s in response to the growing 

concern that wood smoke contributes to ambient air quality-related health problems. 

• Wood smoke contains fine particulates (PM2.5) and also contains other criteria pollutants, persistent 

bioaccumulative air toxics, other air toxics, and greenhouse gases. Organic carbon is emitted from this 

source category along with elemental carbon. 
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• Section 111 of the Clean Air Act (CAA), "Standards of Performance for New Stationary Sources," 

requires EPA to establish federal standards of performance for new sources for source categories which

cause or contribute significantly to air pollution, and which may reasonably be anticipated to endanger 

public health or welfare. 

• Section 111(b)(1)(B) of the CAA mandates that EPA review and, if appropriate, revise existing NSPS at 

least every 8 years. “Standards of Performance for New Residential Wood Heaters” (codified at 40 CFR 

Part 60, Subpart AAA) were promulgated on February 26, 1988. 

• In response to numerous States’ concerns about the contribution of wood smoke emissions to high PM2.5 

ambient concentrations and their requests to update and develop regulations relating to a variety of wood 

combustion devices, EPA conducted an extensive review of the current NSPS. 

• States, environmental groups, and the Hearth, Patio and Barbecue Association (HPBA) have also 

recommended changes to the NSPS. These stakeholders suggested that more recent information and 

technologies justify that the review and revision of the 1988 residential wood heater NSPS are needed to 

capture the improvements in performance of such units. Also, many of these stakeholders have 

encouraged EPA to develop additional NSPS for regulating other residential wood-combustion devices, 

as well as residential devices that burn other fuels, which are in the U.S. market and/or available abroad 

and which are expected to be imported soon. 

• Based on the review of the current NSPS, EPA concluded that revision of the standards is necessary to 

reflect improvements in methods for reducing emissions. In 2011 EPA anticipates proposing revisions to 

the standards for new residential wood combustion devices and additional regulations for new residential 

devices that burn other fuels. 

Status and Proposal Schedule 

• EPA is actively reviewing test methods, including efficiency test methods and discussions 

with HPBA on emissions averaging (burn rate weightings), low burn rate, number of runs, 

time for hot start, caps, degradation, etc. 

• No court-ordered deadline applies to this proposal under consideration. 

• Complete Regulatory Impacts Analysis by September 30, 2010. 

• Conduct Options Selection with Assistant Administrator by December 1, 2010. 

• Conduct Final Agency Review—January 15-February 15, 2011. 

• Publish proposed NSPS Revisions and Related New Standards—June 15, 2011 

• Publish final NSPS Revisions and Related New Standards—July 2012