10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Emission Factors and Optical Properties of Health and Climate Relevant Pollutants Measured in a Multi-year Cookstove Intervention Study in Rural India
MOHAMMAD MAKSIMUL ISLAM, Roshan Wathore, Grishma Jain, Karthik Sethuraman, Hisham Zerriffi, Julian Marshall, Rob Bailis, Andrew Grieshop, North Carolina State University
Abstract Number: 1368 Working Group: Combustion
Abstract Particulate and gaseous pollutants emitted from biomass stoves have adverse health and climatic impacts. Globally over 3 billion people, and majority of people in rural India, use solid fuel cookstoves to meet their household energy demand. Although there are studies showing alarming pollutant emissions associated with biomass stoves in the lab and field settings, there is still little real world in-home cookstove emission measurement data. Moreover, very few studies address seasonality and inter-location variability in emissions. In this study, we characterize cookstove emissions measured during a multi-year intervention study in two rural areas (Kullu in Himachal Pradesh State; Koppal in Karnataka State) in India. This study aims to find an association between adoption of alternative biomass and modern-fuel cookstoves and reduced emissions and exposures.
In the intervention, households chose from a range of stove models (e.g. advanced biomass, liquefied petroleum gas: LPG) for cooking and/or heating in homes. These stoves were typically used along with existing ones, and in-home measurements were conducted before and after selection. The study had three ~3-month-long measurement periods (baseline: BL, follow-up-1: F1, follow-up-2: F2) for each location. The time gap between measurement periods was ~7 months for each location. Most households chose to receive a modern-fuel stove (LPG, electric); fewer households (12.5% in Koppal and 32% in Kullu) selected a biomass stove. However, we conducted 129 emission measurements (54 BL; 31 F1; 44 F2) from traditional stoves (mud stoves & three-stone-fires), 55 (25 BL; 12 F1; 18 F2) from ‘Tandoor’ chimney stoves (Himansu Tandoor & Traditional Tandoor), 44 (4 BL; 17 F1; 23 F2) from LPG stoves, 7 from Envirofit rocket stoves and 12 from others (Prakti & TERI), totaling to 247 tests.
Emission measurements were carried out with a portable instrument (STEMS) that measures real-time concentrations of carbon dioxide, carbon monoxide (CO), particle light scattering and absorption and collects integrated filter samples for gravimetric PM2.5 and Organic/Elemental Carbon (OC/EC) analyses. Mean PM2.5 emission factor (EF) of traditional stoves in Kullu during baseline was 8.1 g/kg, approximately 40% higher than follow-up-1 (4.8 g/kg). Like PM2.5-EF, OC-EF was higher (~40 %) during baseline than follow-up-1 in Kullu. This suggests not only that PM2.5 mass was dominated by the organic fraction but also that OC variability dominates the seasonality in EFs. Significantly higher PM2.5 and CO EFs were observed for traditional stoves in Kullu (>20%; p<0.05) than Koppal during baseline, suggesting substantial inter-location variability in EFs. Among the alternative biomass stoves, the Envirofit had significantly lower CO-EF (14%; p<0.05) relative to traditional stoves in Koppal. However, Himansu Tandoor (improved chimney heating stove) had similar pollutant EFs to traditional stoves in Kullu. LPG had the lowest pollutant EFs, although mean CO-EF was around two times higher compared to lab values in literature, suggesting substantial variability in stove performance. Moderately strong correlation (r2=0.60) between gravimetric PM2.5 concentrations and particle scattering coefficients suggests that optical scattering data can be used as a reasonable proxy for PM2.5 mass. Single scattering albedo was somewhat negatively correlated (r2=0.15) with modified combustion efficiency but more strongly (r2=0.39) with elemental carbon to total carbon ratio (EC/TC), indicating that greater black carbon production was associated with efficient combustion. Preliminary analysis of real-time particle optical properties shows that light scattering particles were emitted more during low MCE events from traditional stoves (without chimney) compared to traditional tandoor stoves (with chimney). Second follow up data are being analyzed, and the seasonality, inter-site variability and the influence of real-time activity on emissions and particle optical properties will be explored using this extensive data set.