November 15, 2012

Gina McCarthy, Assistant Administrator

Office of Air and Radiation

U.S. Environmental Protection Agency

Ariel Rios Building 

1200 Pennsylvania Avenue, N.W.

Mail Code: 6101A

Washington, DC 20460

Re: New Source Performance Standards for Wood-burning Devices

Dear Ms. McCarthy:

The American Lung Association strongly urges the U.S. Environmental Protection 

Agency to propose updated health-protecting New Source Performance 

Standards (NSPS) for residential wood heaters without further delay. We urge 

EPA to swiftly adopt rigorous, health-protective standards for all 

classes of residential wood heaters that require the best emission 

reduction systems. We also urge EPA to develop emissions testing methods 

that reflect real-world performance of residential heating devices. 

Residential wood heaters include open fireplaces, outdoor and indoor wood-fired 

boilers, indoor heaters, furnaces, masonry heaters and wood and pellet stoves. 

The U.S. Census (2011) reports that nearly two percent of all U.S. households 

use wood as a primary heat source. In 2006, one study estimated that 

approximately 14 to 17 million such devices were then in use in the United States

(Johnson, 2006). Annual sales of outdoor wood boilers grew ten-fold between 

2000 and 2005 – a rate suggesting that 500,000 outdoor wood boilers may have 

been in use by 2010 (NESCAUM, 2006; New York State Office of the Attorney 

General, 2008). 

Emissions from Wood-Burning Threaten Public Health

Burning wood produces emissions that are widely recognized as harmful to 

human health. Emissions from woodsmoke, discussed below, include particulate 

matter, carbon monoxide, nitrogen oxides, volatile organic compounds, 

hazardous air pollutants and carcinogens. Many of these emissions can occur in 

both indoor and outdoor environments (Naeher et al., 2007). Woodsmoke is also 

a significant source of many of these pollutants, especially primary particulate 

matter. New source performance standards should recognize the diversity and 

toxicity of these woodsmoke-related air pollutants. 
Gina McCarthy, Assistant Administrator

Office of Air and Radiation

U.S. Environmental Protection Agency

November 15, 2012 ● Page 2

Particulate Matter

The EPA recognized woodsmoke as a major source of particulate matter emissions in the 2009 

Integrated Science Assessment for Particulate Matter (PM ISA, 2009). The PM ISA reports that emissions 

from residential wood burning comprised seven percent (7 %) of the source of anthropogenic emissions 

of primary PM 2.5 in 2002 (PM ISA, 2009). Woodsmoke particles generally fall under one micrometer (1 

μm) in size, making them largely ultrafine particles. Because of their size, woodsmoke particles can be 

transported hundreds of kilometers from the source (Naeher et al., 2007). The EPA concluded in the 

PM ISA that fine particulate matter cause premature death and cardiovascular disease and likely causes 

respiratory harm (PM ISA, 2009). The PM ISA reported studies that specifically found woodsmoke and 

vegetative burning associated with an increased risk of cardiovascular mortality (Mar et al., 2000), as well 

as increased emergency department visits from cardiovascular disease (Sarnat et al., 2008) and 

respiratory diseases (Schreuder et al., 2006). 

Since the EPA completed work on the PM ISA, additional research has provided more information about 

particles from woodsmoke. A major review (Bølling et al., 2009) found evidence that combustion 

conditions, including moisture content, insufficient air, and wood constituents, can impact the 

characteristics of the resulting particles. Bølling et al., (2009) found the lowest particle emissions when 

burning incorporates high temperatures, plentiful supply of oxygen and ample mixing of the air and 

gases.

Carbon Monoxide

Woodsmoke is a primary source of carbon monoxide, as identified in both the EPA’s 2010 Integrated 

Science Assessment for Carbon Monoxide (CO ISA, 2010) and the Agency for Toxic Substances and Disease 

Registry (ATSDR) 2012 Toxicological Profile of Carbon Monoxide (ATSDR, 2012). Carbon monoxide 

emissions from woodsmoke add to the outdoor levels of carbon monoxide, as well as increasing indoor 

concentrations (Naeher et al., 2007). 

High, short-term levels of carbon monoxide can be fatal, and contribute to over 20,000 nonfatal 

emergency room visits each year in the U.S (CDC, 2008; ATSDR, 2012). The CO ISA concluded that 

short-term ambient levels of carbon monoxide are likely to cause cardiovascular morbidity. The CO ISA 

also concluded that the evidence suggests that short-term exposure to outdoor levels of carbon 

monoxide may cause premature death, adverse birth outcomes and developmental effects, harm to the 

central nervous system and respiratory harm. The ATSDR concluded that even low levels of exposure 

to carbon monoxide can impact the cardiovascular and nervous system, as well as the fetus and the 

newborn. Consequently, the ATSDR concludes that even low levels of carbon monoxide cannot be 

assumed to be acceptable: 

Although there may be an exposure level that can be tolerated with minimal risk of adverse 

effects, the currently available toxicological and epidemiological data do not identify such 

minimal risk levels (ATSDR, 2012). 

Nitrogen oxides

The EPA recognized wood smoke, including residential wood burning, as a source of nitrogen oxides in 

the 2008 Integrated Science Assessment of Oxides of Nitrogen—Health Criteria (NOx ISA, 2008). The NOx 

ISA estimated that residential wood burning produced 40,000 metric tons of nitrogen oxides in 2002 
Gina McCarthy, Assistant Administrator

Office of Air and Radiation

U.S. Environmental Protection Agency

November 15, 2012 ● Page 3

(Table 2.2-1). The NOx ISA identified residential wood burning as a source of indoor air levels of 

nitrogen oxides. As discussed in the NOx ISA, the Yale Childhood Asthma Study measured indoor 

levels of NOx by heat source in homes of 888 nonsmoking mothers in Connecticut and Virginia. 

Reporting NOx levels at the 90th percentile levels, Triche et al: (2005) found homes with fireplaces had 

two week average concentrations of 80 ppb NOx and homes with wood stoves had two-week average 

concentrations of 52 ppb NOx. Each hour of use of fireplaces, though not wood stoves, were linked in 

increased cough and sore throat. A review article calculated that using fireplaces in these homes for 

four hours would be expected to increase the risk of such symptoms by 16-20 percent (Naeher et al., 

2007).

Volatile organic compounds, including carcinogens and HAPs 

Woodsmoke contains “many hundreds” of hydrocarbons and oxygenated organics, many of which are 

carcinogens and hazardous air pollutants (Naeher et al., 2007). Benzene, formaldehyde, and 1,3-

butadiene are recognized as known human carcinogens (HHS, 2011). Long-term exposures to benzene 

can cause leukemia, a blood cancer, and other blood disorders such as anemia and depressed 

lymphocyte count in blood. Exposure to formaldehyde can also cause chronic bronchitis and nasal 

epithelial lesions. A recent review of the research found evidence that formaldehyde may increase the 

risk of asthma, particularly in the young (McGwin et al., 2010). 

Woodsmoke contains at least 26 pollutants specified in the Clean Air Act as hazardous (Naeher et al., 

2007). Some include the carcinogens listed above but others have non-carcinogenic impacts. These 

gases can also irritate the eyes, skin, and respiratory tract, impair lung function, and affect vital organs.

Polycyclic aromatic hydrocarbons (PAHs)

Woodsmoke is estimated to contain over 20 different polycyclic aromatic hydrocarbons, or PAHs

(Naeher et al., 2007). A recent review identified some of the most abundant PAHs in woodsmoke as 

naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene. In addition 

two others, benzo(a)pyrene and fluoranthene are carcinogens (Bølling et al., 2009).

Many People Face Higher Risk

Many people are more susceptible to harm from emissions from wood smoke. Large populations face 

higher risk: those at vulnerable life stages, including fetuses, children, teens and adults over age 65; those 

who have chronic lung diseases, such as asthma and chronic obstructive pulmonary disease; those who 

have heart disease, high blood pressure, coronary artery disease and congestive heart failure; diabetics; 

and those with low incomes (PM ISA, 2009). 

Initial Recommendations for NSPS standards

Given the evidence of that wood-burning emits so many hazardous air pollutants, including carcinogens, 

the American Lung Association recommends that EPA propose NSPS that are based in each new unit 

meeting the average emission rate for the top twelve percent (12 %) of similar units. That standard 

would be comparable to other new sources and reductions in existing sources of hazardous air 

pollutants. Since so many units can currently meet those limits, not only is the technology available, it is 

already in wide use. 
Gina McCarthy, Assistant Administrator

Office of Air and Radiation

U.S. Environmental Protection Agency

November 15, 2012 ● Page 4

The Lung Association also strongly urges that standards be set on three major categories of uses, rather 

than the myriad varieties of wood-burning devices now available. Groups such as “room heating,” 

“central heating” and “thermal storage units” would allow much more consistency among standards for 

units with similar functions. Three categories would ensure greater public health protection regardless 

of the predominant use of a specific device in a community. 

As noted earlier, burning wood can produce high levels of carbon monoxide that can place particular

risk to the public. The Lung Association strongly recommends that EPA establish a specific carbon 

monoxide emissions standard for these devices. 

EPA Needs To Take Action Now

The EPA set the current NSPS for wood-burning devices nearly a quarter century ago. That year, 1988, 

was six years before the first of the landmark studies that taught that particulate matter can be deadly. 

Since then, research into the pollutants from wood-burning has grown rapidly, creating abundant 

evidence that the standards are woefully out of date. Technology to reduce and control emission has 

expanded the ability to protect human health. Still, the NSPS reflect the limited understanding from a 

generation ago. 

The American Lung Association calls on the EPA to move swiftly to adopt rigorous, health-protective 

standards for all classes of residential wood heaters. These standards should require the best emission 

reduction systems that reflect real-world performance of residential heating devices. Until that happens, 

these devices will continue to be built and installed, compounding the outdoor problem and causing 

people to mistakenly bring harmful sources of pollution directly into their homes. That reality will make 

it ever harder to protect the health of the public. 

Now is the time for the EPA to act. We strongly urge the EPA to propose standards that protect public 

health. 

Sincerely,

Paul G. Billings

Senior Vice President

Advocacy and Education

CC: Steve Page, Director, Office of Air Quality Planning and Standards, U.S. EPA

Arthur Marin, Executive Director, NESCAUM

Dan Johnson, Executive Director, WESTAR
Gina McCarthy, Assistant Administrator

Office of Air and Radiation

U.S. Environmental Protection Agency

November 15, 2012 ● Page 5

References

Agency for Toxic Substances and Disease Registry (ATSDR). 2012. Toxicological profile for Carbon 

Monoxide.. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service. Web 

link: http://www.atsdr.cdc.gov/ToxProfiles/tp201.pdf [Accessed: November 10, 2012].

Bølling AK, Pagels J, Yttri KE, Barregard L, Sallsten G, Schwarze PE, Boman C. 2009. Health effects of 

residential wood smoke particles: the importance of combustion conditions and physicochemical particle 

properties. Particle and Fibre Toxicology; 6: 29.

Centers for Disease Control and Prevention (CDC). 2008. Nonfatal, unintentional, non fire-related 

carbon monoxide exposures United States, 20042006. Journal of the American Medical Association

300(20):2362-2363.

Johnson PRS. 2006. In-Field Ambient Fine Particle Monitoring of an Outdoor Wood Boiler: Public Health 

Concerns, Human and Ecological Risk Assessment 1153, 1156.

Mar TF, Norris GA, Koenig JQ, Larson TV. 2000. Association between Air Pollution and Mortality in 

Phoenix, 1995-1997. Environmental Health Perspectives. 108(4): 347-353.

McGwin G, Lienert J, Kennedy JI. 2010. Formaldehyde Exposure and Asthma in Children: A Systematic 

Review. Environmental Health Perspectives. 118(3): 313-317.

Naeher LP, Brauer M, Lipsett M, Zelikoff JT, Simpson CD, Koenig JQ, Smith KR. 2007. Woodsmoke 

Health Effects: A Review. Inhalation Toxicology. 19:67-106.

NESCAUM, Assessment of Outdoor Wood-Fired Boilers, 2006. Page 3-3. Available at: 

http://www.nescaum.org/documents/assessment-of-outdoor-wood-fired-boilers 

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

York State. 2008. (Page 5. 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).

Sarnet JA, Marmur A, Klein M, Kim E, Russell AG, Sarnet SE, Mulholland JA, Hopke PK, Tolbert PE. 

2008.Fine particle sources and cardiorespiratory morbidity: An application of chemical mass balance and 

factor analytical source-apportionment methods. Environmental Health Perspectives. 116: 459-466.

Schreuder AB, Larson TV, Sheppard L, Claiborn CS. 2006. Ambient woodsmoke and associated 

respiratory emergency department visits in Spokane, Washington. International Journal of Occupational 

and Environmental Health. 12(2):147-53.

Triche EW, BelangerK, Bracken MB, et al. 2005. Indoor heating sources and respiratory symptoms in 

nonsmoking women. Epidemiology. 16(3): 377-384.
Gina McCarthy, Assistant Administrator

Office of Air and Radiation

U.S. Environmental Protection Agency

November 15, 2012 ● Page 6

U.S. Census Bureau. 2011 American Housing Survey for the United States. Accessed at 

http://www.census.gov/housing/ahs/files/ahs11/National2011.xls.

U.S. Department of Health and Human Services (HHS). National Toxicology Program. 2011. Report on 

Carcinogens, Twelfth Edition. Research Triangle Park, NC: U.S. Department of Health and Human 

Services.

U.S. Environmental Protection Agency, Integrated Science Assessment for Particulate Matter. 2009. 

Figure 3-3.

U.S. Environmental Protection Agency, Integrated Science Assessment for Carbon Monoxide, 2010.

U.S. Environmental Protection Agency. Integrated Science Assessment for Oxides of Nitrogen-Health 

Criteria. 2008.