John A. Cooper, APCA JOURNAL, Vol. 30, No. 8, August 1980, Oregon Graduate Center
Environmental Impact of Residential Wood Combustion Emissions and its Implications
Currently available information suggests a substantial environmental impact from residential wood combustion emissions. Air pollution from this source is wide. spread and increasing. Current ambient measurements, surveys, ant model predictions indicate winter respirable (<2 ~m) emissions from residential wood combustion can easily exceed all other sources. Both the chemical potency and deliverability of the emissions from this source are of concern. The emissions are almost entirely in the inhalable size range and contain toxic and priority pollutants, carcinogens, cocarcinoogens, cilia toxic, mucus coagulating agents, and other respiratory irritants such as phenols, aldehydes, etc. This source is contributing substantially to the nonattainment of current particulate, carbon monoxide, and hydrocarbon ambient air quality standards and will almost certainly have a significant impact on potential future standards such as inhalable particulates visibility, and other chemically specific standards. Emission from this growing source is likely to require additional expenditures by industry for air pollution control equipment in nonattainment areas.
Man has been exposed to a large number of complex and hazardous chemicals from forest and domestic fires throughout his evolution. Thus, environmental concern over increasing use of wood as a residential energy source is not exposure to a new form of air pollutant. but is, instead, concern over the level of exposure and its impact on public health. current and future ambient air quality standards, and industrial growth. Increasing costs of energy, decreasing availability of fossil fuels, and government encouragement will assure the continued growth of this source of pollution over the next few years. This dramatic shift in energy utilization, however, is being encouraged without an adequate understanding of either the environmental impact or the total costs and benefits. Our forests and their wood waste. are a vital national resource and their use for single family residential space heating is just one of many possible options. The environmental impact is an essential component in the cost benefit analysis ant effective decisions relative to the use of this source of building materials, chemicals, and energy will require an accurate understanding of their impact on the environment.
Currently available information on the impact of residential wood combustion (RWC) sources on air quality is minimal and previously available impact assessment methods inadequate. Recently developed and applies assessment methods using chemical masi balance (CMB) and carbonl! measurements by Cooper, et al have shown promise of improving our understanding and impact assessment capabilities.
The primary objectives of this presentation are to review the available information on potential environmental impacts, note areas where conflicts are likely, and suggest areas of future research.
Thank you to Armidale Air Quality Group for the following work in transcribing this paper's highlights and relating it to Zeedikj's work and in red you will see how they relate the numbers to Australia's wood stove regulations.
Cooper J.A., Environmental Impact of Residential Wood Combustion Emissions and its Implications, Air Pollution Control Association Journal, 30 (8), 855-861, 1980 Aug.
The full text as generated by a computer scan.
"The chemical products formed in the combustion of wood have been studied primarily in terms of the major products of combustions such as water and carbon dioxide and minor components such as CO, HCl, SOx, NOx, etc. Two recent studies however measured over a hundred different chemicals and compound groups in emissions from burning wood and wood-burning stoves. The results from these studies showed smoke from wood and wood-burning stoves and fireplaces contained
Other toxic gases such as CO, noxious and respiratory irritants such as aldehydes, phenols, etc were also found. Even dioxins have been identified in fireplace soot."
|Chemical Species||g/kg wood||% particulates||g/kg wood||% particulates|
|Polycyclic organic material||0.3||3.5||0.03||0.3|
Note: This paper was published in 1980. An AS4013 stove must emit less than 5.5 g/kg of particulates, averaged over low, medium and high burn rates. Thus a correctly-operated AS4013 stove should have at least 35% fewer emissions. However, low burn rates produce significantly worse emissions. A stove rated at 5 g/kg would probably emit similar amounts of pollution to the above table on low burn rate. If operated incorrectly (eg by loading wood and not keeping on the highest possible setting until 20% of wood had been consumed), emissions could be 10 times higher than the table.
Polycyclic aromatic hydrocarcarbon emissions from woodstoves vs open fires and enclosed coal stoves was also investigated by: I H Zeedikj (1985). Polycyclic armomatic hydrocarbon concentrations in smoke aerosol of domestic stoves burning wood and coal. Eindhoven University of Technology, Dept. Chemical Engineering, Laboratory of Instrumental ANalysis, PO Box 153, The Netherlands.
This extract shows Table 3 from his paper. Zeedikj notes that polycyclic aromatic hydrocarcarbon (PAH) emissions from woodstoves vary a factor of 2.4, according to the burn rate and the burn cycle. Emissions are much lower in the latter part of the cycle. Zeedikj reported average over all burn rates and sampled the entire cycle. This, or simple sampling variation, may explain the difference between estimates of 5.8 mg of benzo(a)pyrene per kg of fuel from Zeedijk vs 2.5 mg/kg from Cooper above.