April 29, 2008 

Steve Page, Director 

Office of Air Quality Planning and Standards 

U.S. Environmental Protection Agency 

Mail Code: C404-04 

Research Triangle Park, North Carolina 27711 

Re: Performance Standards for Wood -burning Devices 

Dear Mr. Page: 

The Western States Air Resources Council (WESTAR) and the Northeast States for 

Coordinated Air Use Management (NESCAUM) strongly urge the U.S. Environmental 

Protection Agency (EPA) to update and develop regulations relating to a variety of wood 

combustion devices. The recently revised National Ambient Air Quality Standard 

(NAAQS) for fine particulate matter (PM2.5) recognizes the public health dangers of 

excessive fine particulate matter. Unfortunately, many communities throughout the 

country are measuring ambient conditions above or very close to that new standard. In 

many instances, emissions from wood smoke are a significant contributor to those high 

PM2.5 levels. 

Currently, federal regulations only target a limited universe of wood burning sources, via 

the New Source Performance Standards (NSPS) for residential wood heaters (i.e., indoor 

wood stoves), major New Source Review, and the Maximum Achievable Control 

Technology (MACT) program for boilers. These regulations, along with state and local 

minor source permitting, exempt a significant number of devices that greatly, and 

adversely, affect the environment and public health. 

Indoor Residential Wood Heating Devices

The Residential Wood Heater NSPS, which was developed in 1988 and implemented fully 

by 1992, set emission standards for indoor wood stoves but excluded a broader suite of 

residential wood heating devices (RWDs). In addition, wood heat technology has 

advanced significantly since the existing standards were phased in almost twenty years 

ago. New technologies for regulated RWDs are commercially available now in the U.S. 

that perform at significantly lower grams-per-hour emission rates than required under the 

existing indoor wood stove standard. Furthermore, even greater performance can be 
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achieved by technologies employed in Europe. The Clean Air Act requires review of a 

NSPS every eight years unless determined “that review is not appropriate in light of 

readily available information on the efficacy of such standard.” At a minimum, given the 

current body of evidence, review and revision of the current residential wood heater/indoor 

wood stove NSPS to capture the broader suite of RWDs is appropriate and warranted. 

A critical concern of our states is the lack of regulations for a broad variety of RWDs that 

are available for sale and not addressed by the NSPS at all; these include fireplaces, 

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

These devices are making their way to market and we urge EPA to develop standards for 

them. 

As many state and local agencies move forward with strategies to meet the revised PM2.5

NAAQS, they are implementing new or enhancing their existing “wood stove change-out” 

programs. These efforts will reduce the number of high-polluting uncertified wood stoves 

in local communities. Without new and revised standards, however, newly installed 

devices may not be the cleanest available in the marketplace. Ensuring that the change-out 

programs are replacing uncertified stoves with the cleanest-burning devices available in the 

marketplace would assure that public and private dollars are spent wisely and on the best 

possible public health and pollution control outcomes. 

In addition, we urge EPA to expand change-out efforts to include other RWDs by 

supporting change-outs of all outmoded RWD technologies. To support that outcome, we 

ask EPA to update and develop standards for RWDs in the same manner that emission 

standards are updated for mobile source technologies. Newer models should be required to 

meet lowered emission limits as technology permits, creating a cleaner “fleet” of devices 

over time. Given that cleaner-burning technologies are readily available in the 

marketplace, it is a lost public health opportunity to allow the continued manufacture and 

sale of equipment with low-end, higher-polluting technology that will remain in homes for 

years to come. 

Outdoor Residential Wood Heating Devices

One significant area of concern is outdoor wood-fired boilers (or outdoor wood-fired 

hydronic heaters -- OWHHs). These units represent a new and growing public health 

concern in both the East and West. They can be highly-polluting and, when improperly 

used, subject neighbors, neighborhoods, and entire communities to serious impacts from 

particulate matter and products of incomplete combustion. While EPA’s voluntary 

program has made great progress towards encouraging the development of cleaner 

OWHHs, it has not banned the sale of new units with older, dirtier designs and is not a 

mandatory program. We therefore urge EPA begin efforts to develop a technical basis for 

regulating emissions from these devices. 
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Small Commercial and Institutional Wood Boilers

We also urge EPA to develop emission standards for small commercial and institutional 

wood boilers, especially those being marketed for use in schools and hospitals. As the 

price of fossil fuels increases, many schools and hospitals are considering or installing 

wood-fired boilers. In many instances, these units are replacing natural gas-fired boilers 

that emit less particulate matter and other criteria and air toxic pollutants than wood-fired 

boilers. For example, a report developed for Wisconsin Division of Energy reported that 

more than 300 schools -- representing more than 25 percent of the schools currently 

heating with natural gas -- would find it economically beneficial to switch to wood-fired 

boilers. Schools, however, are receiving little to no information on the adverse health 

effects caused by smoke from these boilers, nor are they told of the potential costs of future 

air pollution control equipment once these dirtier boilers are installed. 

Unfortunately, technical data characterizing emissions from these units and analyses 

regarding the efficacy of pollution controls is lacking. This impedes both state and federal 

activities to properly address these emission sources. Therefore, it is critical that EPA 

direct resources to properly investigate this issue. As energy and forestry programs move 

forward with their support of these programs, and as we move towards greater use of 

biomass resources for space heating purposes, we must have methods to ensure protection 

from exposure to toxic and criteria air pollutant emissions. We therefore urge EPA to 

immediately invest in analyses to create a technical basis for characterizing wood boiler 

emissions to support state and federal regulations for these units. 

Conclusion

In light of the new PM2.5 NAAQS and the preponderance of wood smoke as a source of 

fine particle pollution in the U.S., further tightening of standards for wood heating 

appliances is essential. Improved standards for new wood heating devices would provide a 

much needed tool for states and local communities to use in addressing the growth of 

pollution from these sources. Typically, EPA regulations take six to seven years to 

complete. If EPA were to begin work now on a NSPS, a likely implementation date would 

be around 2015. However, many federal, state, and local agencies are making investments 

in renewable energy programs now. If not implemented properly, these programs are 

likely to encourage increases in air pollution, especially air toxics and particulate matter. 

Therefore, it is essential that EPA provide guidance now during this crucial time. 

 
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We urge you to move forward promptly on these important issues. We would be happy to 

meet with you to discuss this issue in greater detail. If you have any questions, please 

contact either Arthur Marin at 617-259-2017 or Dan Johnson at 206-254-9145. 

Sincerely, 

 

Arthur Marin, Executive Director Dan Johnson, Executive Director 

NESCAUM WESTAR 

cc: Rob Brenner 

 Greg Green