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UBC Theses and Dissertations

Characterization of ultrafine particulate matter from traditional and improved biomass cookstoves Just, Brian Gary


Billions of people worldwide use biomass fires or cookstoves on a daily basis, with significant resultant contributions to emissions of global carbonaceous aerosols. The use of biomass as a fuel has an impact on local ecosystems, contributes to CO2 levels in the atmosphere, and black carbon (BC) and organic carbon (OC) affect the earth’s radiative balance. Widespread initiatives, including carbon funding programs, propose to replace traditional “three-stone” open fires with “improved” cookstoves designed to reduce fuel usage. While numerous studies investigate cookstove efficiency and publish emissions factors for gaseous pollutants and overall particulate matter (PM), there is a lack of focus on the size and nature of ultrafine particulate (UFP) emissions. This paper compares ultrafine emissions during steady combustion from a traditional three-stone fire and two improved stoves: a Rocket stove (“Chulika”) and a Gasifier stove (“Oorja”). An AVL emissions bench measured gaseous products. PM instrumentation included a TSI SMPS, TSI APS, TSI DustTrak DRX, Magee Scientific Aethalometer, and 47mm PTFE and quartz filters; a thermophoretic sampling device was employed to gather material for PM imaging using transmission electron microscopy (TEM). The improved cookstoves demonstrated high combustion efficiency compared to the three-stone fire and are likely to reduce biomass consumption. Additionally, emitted PM mass was reduced by a significant amount. PM emissions from improved stoves had a higher proportion of BC compared with total PM, though there was relatively little variation in overall BC levels. The reduction in highly scattering OC that would accompany a large-scale shift towards usage of improved stoves could affect the earth’s radiative balance, but this merits investigation with consideration to other particle characteristics. Primary particles emitted from the improved stoves were smaller than those from the three-stone fire and appeared slightly less likely to coagulate into chain agglomerates. The observed shift towards greater quantities of smaller nanometer-sized particles could pose health concerns and is a point for further consideration by health scientists and reinforces the need for adequate ventilation for all cookstoves, independent of type.

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