Rising fuel prices have kicked up installations of outdoor wood boilers in North America. But a vacuum in EPA regulation has left residents breathing lifethreatening smoke from their neighbor’s OWB with little recourse but the courts.
EPA has a certification program for indoor woodstoves but for OWBs, maintains only a list of Phase 2 qualified hydronic heaters. The most complained about OWBs in our community have been two OWBs by Central Boiler model 2300, listed by EPA as Phase 2 qualified. The Federal government continues to give tax credits for purchase of a “qualified biomass burning stove” including Phase 2.
EPA has proposed to publish Residential Wood Heater New Source Performance Standards in the Federal Register June 2011 for public comment and may publish the final rule in July 2012. Don’t hold your breath; the new standard is proposed to be higher (less protective) than the tested emissions from a Central Boiler 2300.
Emissions tests methods are standardized and run with cribs of seasoned oak, a fuel not available in Interior Alaska. Thus, the results serve for comparison purposes but do not reflect real-world misuse, actual smoke emissions, or cumulative impacts of multiple units in one area. Operator controlled variables include load size, moisture content, wood species, fuel size, oxygen supply, heat demand, and chimney height. Atmospheric conditions such as cold temperature inversions with low dispersion pool emissions near the source creating PM 2.5 hotspots, especially in areas of low-lying topography.
Painfully high PM 2.5 concentrations on a regular bad winter air day in Fairbanks and North Pole are higher than other communities known for having the worst fine particulate pollution. See previous post: Highest Fine Particulate Pollution in the Nation.
More accurately called wood-fired hydronic heaters because they don’t boil, these units operate without any local or state permits and release fine particulate (PM 2.5) pollution as well as these four polycyclic aromatic hydrocarbon compounds classified as probable human carcinogens:
- Benzo[k]fluoranthene and
- Indeno[1,2,3 cd]pyrene
Two articles from the January 2011 issue of EM, published by the Air and Waste Management Association, used with permission from EM and the authors, offer sobering considerations for residents and communities enduring substantial hazardous emissions from wood-fired hydronic heaters. A third report by one of the same authors further examines the topic.
Outdoor Wood Boilers: How Biomass Can Go Wrong by Jane C. Barton 2011
Adverse Health Effects: Exposure Threats of OWBs by Philip R. S. Johnson 2011
Health effects and exposure risk of wood smoke by Philip R. S. Johnson 2007
Findings from these Reports
A quarter century of medical, toxicological, and epidemiological investigation has conclusively found that exposure to residential wood smoke is hazardous to human health; impacts can range from acute respiratory distress in children to cancer in adults.
Washington State standards and a growing number of community OWB bans across North America have effectively achieved adequate public health protection by means of eliminating exposures.
A 2009 health consultation prepared by the Michigan Department of Community Health with the Agency of Toxic Substances and Disease Registry concluded that the operation of an OWB in a residential neighborhood presented an ‘urgent public health hazard.’ [A single OWB. What would they call multiple clusters of unregulated OWBs, some burning coal, in our suburban neighborhoods and near schools? What do you call it?]
Tiny particles bypass upper pulmonary tracheal defenses and instead deposit exogenous materials into alveolar tissue where gas exchange occurs, one of the most vulnerable portals of the body.
In addition to PM 2.5 compounds—some with mutagenic or carcinogenic properties—are found in wood smoke emissions, including acrolein, carbon monoxide, polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs; e.g., benzene and formaldehyde) and other toxic combustion products.
Sub-daily peaks masked by daily averaging – The increasing use of continuous PM 2.5 monitoring over the past decade has led to findings of health associations at time scales of less than 24-hour averages. Several studies show acute cardiac and pulmonary adverse effects from exposures at mean and maximum hourly metrics, sometimes with greater significance than traditional daily averages…. Current evidence suggests that the PM 2.5 NAAQA [24-hour average standard of 35 μg/m3] is not an effective means to protect populations from peaking wood smoke exposures, especially vulnerable subgroups, including asthmatics, children, and the elderly.
Susceptible populations at greater risk of experiencing health effects from inhalation of PM 2.5 emissions and other air pollutants commonly measured in wood smoke comprise a large fraction of the general population, including pregnant women, infant, children, and elderly subgroups; persons of any age group with preexisting respiratory, cardiac, and diabetes disease; and persons experiencing high exposures. [Does this mean, due to our local extremely high exposures, we’re all in the “sensitive groups” category?]
Because wood combustion aerosols readily infiltrate through building envelopes, ambient RWC emissions, including OWBs, are an indoor air quality threat. Indoor exposure to ambient-derived wood smoke have been associated with adverse health effects. [Building ventilation, essential in the far north, has drawn smoke-filled outdoor air inside homes and schools.]