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November 9, 2012

Gina McCarthy

Assistant Administrator

EPA Office of Air and Radiation

USEPA Headquarters

Ariel Rios Building

1200 Pennsylvania Avenue, N.W.

Mail Code: 6101A

Washington, DC 20460

Dear Assistant Administrator McCarthy:

On behalf of the millions of Americans represented by our public health and 

environmental organizations, we strongly urge the U.S. Environmental Protection 

Agency (EPA) to propose revised health-protecting New Source Performance Standards

(NSPS) for highly polluting wood combustion devices without delay.

Our request follows repeated calls by states, clean air agencies and other groups to clean 

up harmful pollution from such as wood combustion devices. In 2005, the states of New 

York, Connecticut, Maryland, Massachusetts, Michigan, New Jersey and Vermont and 

the Northeast States for Coordinated Air Use Management (NESCAUM) petitioned the 

agency to list outdoor wood boilers, also called hydronic heaters, as a stationary source

category and promulgate strong NSPS for the devices.1 NESCAUM and the Western 

States Air Resources Council (WESTAR) sent letters to EPA in 2008 and 2012 

requesting the agency update the NSPS for highly polluting wood combustion devices.

2

And on August 28, 2012, the Environmental Council of the States (ECOS) approved a 

resolution calling on EPA to “act immediately to update the NSPS establishing health 

protective emission limits” for wood combustion devices.3 The agency has received 

numerous other letters over the last decade from citizens, cities, states, air agencies and 

health and environmental groups impacted by and concerned about the harmful pollution 

from these devices.

These concerns about the air pollution impacts from governments and citizens across the 

country reflect the widespread nature of smoke emissions from highly polluting wood 

combustion devices, and the serious health problems that this pollution creates for 

families and communities. Wood combustion devices include outdoor and indoor woodfired boilers (hydronic heaters); indoor heaters; furnaces; masonry heaters; and cook 

stoves. It is estimated that approximately 14 to 17 million such devices are now in use in 

the United States.4 Hydronic heaters in particular have rapidly increased in use in recent 

years, with annual sales growing ten-fold between 2000 and 2005 – a rate suggesting the 

installed number of outdoor wood boilers now numbers in the hundreds of thousands.5 
2

Collectively, highly polluting wood combustion devices represent a large and growing 

source of several airborne contaminants that directly endanger human health, including 

fine particulate matter (PM2.5), carbon monoxide, volatile organic compounds, polycylic 

aromatic hydrocarbons (PAH), and chlorinated dioxins.6 These devices are one of the 

single largest direct sources of anthropogenic PM2.5 in the nation, emitting more than 

340,000 tons per year or more than 17 percent of the national anthropogenic total.7 

Smoke from high-emission wood combustion devices represents an even larger share of 

particulate pollution in areas of the country where such devices are commonly used, such 

as the Pacific Northwest, Midwest, and Northeast. For example, EPA has estimated that 

smoke from these devices contributes 25% of wintertime PM2.5 pollution in parts of New 

Hampshire and Wisconsin, and more than 50% of wintertime PM2.5 in Tacoma, 

Washington and Sacramento, California.8 Regional monitoring commissioned by the 

New York Energy Research and Development Authority has also found that smoke from

highly-polluting wood combustion devices is responsible for potentially dangerous shortterm “spikes” in PM2.5 concentrations in towns and villages in rural areas.9

 

EPA has also concluded that smoke from high-emission wood combustion devices

accounts for a significant proportion of nationwide emissions of certain hazardous air 

pollutants – including 44% of total stationary and mobile emissions of polycyclic organic 

matter, and 62% of total PAH emissions,

10 many of which are known or probable human 

carcinogens.

11 

A substantial body of scientific literature indicates that emissions from highly polluting 

wood combustion devices are associated with increased incidence of asthma and other 

respiratory problems, especially in young children.12 Particulates emitted by these 

devices, especially hydronic heaters, have health impacts disproportionate to the absolute 

level of emissions because these sources are located close to the ground and in close 

proximity to homes and businesses. 

The first and only time EPA promulgated NSPS for these devices was in 1988 – despite 

EPA’s clear legal mandate under the Clean Air Act to review and update its NSPS every 

eight years.

13 Moreover, the current antiquated NSPS apply only to a narrowly defined 

subset of new wood combustion devices, and do not apply to other increasingly popular 

devices such as hydronic heaters, pellet stoves and masonry heaters.14 Yet over the 

nearly quarter century since EPA promulgated the NSPS, advanced technologies to 

significantly reduce emissions from all classes of wood combustion devices have been 

developed and demonstrated. Many wood combustion devices with emission rates far 

below EPA’s current standards are on shelves and in use today. Furthermore, standards 

far more protective than the current NSPS have been successfully implemented in the 

European Union, leading to a dramatic improvement in the efficiency of these devices 

and a 99% reduction in their carbon monoxide emissions.15 Far from harming the market 

for wood combustion devices, these more protective standards have been accompanied by 

rising demand. The Agency has failed to uphold its legal obligation to update the NSPS 

to reflect such developments and ensure continued reductions in emissions from these 

devices. We respectfully request your leadership in addressing this serious air pollution 

problem. 
3

In the absence of EPA action, states and localities have been forced to take steps on their 

own to protect their residents from smoke emitted by highly-polluting wood combustion 

devices. Washington State has adopted more protective emissions standards, and some 

jurisdictions have banned the use of hydronic heaters.

16 Such state and local clean air 

measures are vital, but EPA leadership is also essential to ensure all Americans are 

protected from these harmful contaminants — especially given the far-reaching market 

for wood combustion devices. Accordingly, we respectfully urge EPA to swiftly adopt 

rigorous, health-protective standards for highly polluting wood combustion devices

that reflect the best system of emission reduction that has been adequately 

demonstrated. We also urge EPA to develop emissions testing methods that reflect the 

true, real-world performance of such devices. This will allow EPA to accurately identify 

the top performing systems. 

EPA’s recent proposal to strengthen the national ambient air quality standard for fine 

particulate matter presents the most recent science on the harmful health impacts of 

particulate pollution and underscores the need to update the NSPS. We strongly and 

respectfully request EPA promulgate health protective standards that include all highly 

polluting wood combustion devices and reflect the best system of emission reduction.

These standards are necessary to protect all Americans from the harmful health impacts 

of wood combustion and help states meet life-saving, health-based ambient air quality 

standards.

Sincerely,

Center for Biological Diversity

Clean Air Council

Clean Air Task Force

Clean Air Watch

Clean Water Action

Earthjustice

Environment and Human Health Inc.

Environmental Advocates of New York

Environmental Defense Fund

Environmental Law and Policy Center

Families for Clean Air

Group Against Smog and Pollution (GASP)

Hoosier Environmental Council

Idaho Conservation League

Izaak Walton League of America, Porter County Chapter (IN)

Midwest Environmental Advocates

Minnesota Center for Environmental Advocacy

Moms Clean Air Force

Natural Resources Defense Council

Oregon Environmental Council
4

Safe Air for Everyone

Save Our Summers Northwest

Sierra Club

Wyoming Outdoor Council

Cc: 

Steve Page, Director, OAQPS

Peter Tsirigotis, OAQPS

Lydia Wegman, OAQPS

Lorie Schmidt, OGC

																																																						 1 Letter from New York Attorney General Eliot Spitzer to EPA Administrator Stephen L. Johnson, Petition 

for rulemaking under 42 U.S.C. § 7411(b)(1) Regarding Outdoor Wood Boilers, August 11, 2005. 2 Letter from NESCAUM Executive Director Arthur Marin and WESTAR Executive Director Dan Johnson 

to EPA OAQPS Director Steve Page, Performance Standards for Wood -burning Devices, April 29, 2008; 

Letter from NESCAUM Executive Director Arthur Marin and WESTAR Executive Director Dan Johnson 

to EPA Administrator Lisa Jackson, New Source Performance Standard for Residential Wood Burning 

Devices, August 3, 2012. 3 ECOS Resolution 12-3, REGARDING NEW SOURCE PERFORMANCE STANDARDS FOR 

RESIDENTIAL WOOD BURNING DEVICES, Approved August 28, 2012, Colorado Springs, Colorado. 4 Philip R.S. Johnson, In-Field Ambient Fine Particle Monitoring of an Outdoor Wood Boiler: Public 

Health Concerns, Human & Ecol. Risk Assessment 1153, 1156 (2006) 5 NESCAUM, Assessment of Outdoor Wood-Fired Boilers, Page 3-3 (2006). Available at: 

http://www.nescaum.org/documents/assessment-of-outdoor-wood-fired-boilers See also New York State 

Office of the Attorney General, Smoke Gets in Your Lungs: Outdoor Wood Boilers in New York State, Page 

5 (Mar. 2008) (estimating 22% annual growth rate in national OWB sales for 2004-2007, and estimating 

that over 188,000 OWBs were installed from 1999 to 2007).

6 See, e.g., Gil Wood, Residential Wood Heaters New Source Performance Standards (NSPS): Current 

Draft Revisions, Slide 4 (presentation dated Mar. 1, 2011) (Wood 2011); Gil Wood, Residential Wood 

Heaters New Source Performance Standards (NSPS): Public Outreach on Draft Proposed Rule, Slides 5-6 

(presentation dated Feb. 9, 2012) (Wood 2012).

7 U.S. EPA, National Emissions Inventory 2008 accessed on September 11, 2012. 

8 Wood 2012, Slide 6.

9 See NYSERDA, Spatial Modeling and Monitoring of Residential Woodsmoke Across a Non-Urban 

Upstate New York Region xvii-xix, 4-1 (Feb. 2010) (Finding that in a seven-county area of upstate New 

York, “very high spikes in woodsmoke concentrations” of over 100 micrograms per cubic meter were 

observed and that 26% of the monitored population was exposed to elevated residential woodsmoke). See 

also David R. Brown & Nancy Alderman, The Dangers to Health From Outdoor Wood Furnaces 16 

(2010) (finding short-term levels of PM2.5 that were between four times and nine times EPA’s 24-hour 

National Ambient Air Quality Standard in four homes located near outdoor wood boilers). 10 Wood 2011. 11 EPA, Technology Transfer Network Air Toxics Website, Polycyclic Organic Matter (POM). Available 

at: http://www.epa.gov/ttn/atw/hlthef/polycycl.html Center for Disease Control, Toxic Substances Portal: 

Polycyclic Aromatic Hydrocarbons (PAH). Available at: 

http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=121&tid=25

Rybicki BA, Neslund-Dudas C, Nock NL, Schultz LR, Eklund L, Rosbolt J, Bock CH, Monaghan KG. 

2006. Prostate cancer risk from occupational exposure to polycyclic aromatic hydrocarbons interacting with 

the GSTP1 Ile105Val polymorphism. Cancer Detect Prev. 30:412-422. 12 See, e.g., Luke P. Naeher et al., Woodsmoke Health Effects: A Review, 19 Inhalation Toxicology 67, 82-

87 (2006) (reviewing studies of wood smoke exposure and health impacts); Johnson, 1154-55 (“Numerous 
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studies have found that exposure to the concentrations and durations of wood smoke associated with 

residential wood burning can cause a variety of adverse respiratory effects. These include increases in 

respiratory symptoms, decreases in lung function, visits to emergency departments, and hospitalizations”); 

Pernille Hogh Danielsen et al., Oxidative Stress, DNA Damage, and Inflammation Induced by Ambient Air 

and Wood Smoke Particulate Matter in Human A549 and THP-1 Cell Lines, 24 Chem. Res. Toxicol. 168 

(2011). 13 42 U.S.C. § 7411(b)(1)(B). 14 See 40 C.F.R. §§ 60.530(h) (exemptions for fireplaces, boilers, furnaces, and cookstoves), 60.531 

(defining “residential wood heater”).

15 NESCAUM et. al., Biomass Boiler and Furnace Emissions and Safety Regulations in the Northeast 

States: Evaluation and Options for Regional Consistency (2009). 16 Utah Air Quality Rule R307-208. Available at: 

http://www.rules.utah.gov/publicat/bulletin/2012/20120801/36481.htm

Wood Stove Information, Washington State Department of Ecology. Available at:

http://www.ecy.wa.gov/programs/air/indoor_woodsmoke/wood_smoke_page.htm

Wood-fired Hydronic Heaters Information, Washington State Department of Ecology. Available at: 

http://www.ecy.wa.gov/programs/air/outdoor_woodsmoke/Wood_boilers.htm