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Health impacts due to exposure to biomass combustion: a study over Karauli, Rajasthan

Student Name: Ms Snehlata Tigala
Guide: Dr Kamna Sachdeva
Year of completion: 2019


A plethora of literature exists on the health impacts due to exposure to biomass combustion. Traditional cookstove using solid biomass fuel have a fundamental drawback pertaining to its energy inefficient fuel pattern and stove type. Therefore, it is paramount to understand the dynamics of the household energy system and the concomitant health problems. Although, most related studies in the health sector are either based on social sciences, epidemiology, immunology, or modeling, however, the present work adopts a multi-disciplinary approach to explore and assess health risks associated with exposure. The health impacts due to biomass combustion have been evaluated through the analysis of secondary databases, generation of primary datasets, and application of scientific models. A parsimonious methodology has been employed through the use of existing dose-response models and lung deposition models to understand the dosage and regional deposition ensuing from commonly used cooking fuels. Throughout the course of this study, LPG fuel has been used to draw a comparison between clean and unclean cooking fuel. Investigations from the study revealed that the socio-cultural, financial, physiological, and environmental parameters modulate the exposure either individually or in totality.

The study demonstrates that the assortment of various biophysical and socio-cultural determinants, concoct and reinforce the challenges within the rural communities. Direct personal experiences of the respondents were formative in highlighting the predicament of the individuals exposed to indoor biomass combustion. The overall high aerosol levels were suggestive of biomass combustion as a major contributor to the air quality of the region. The air quality assessment further validated that the major source of air pollution was biomass combustion (53%). The everyday domestic energy needs were fulfilled through indoor combustion of cooking fuel, although, the fuel as well as the stove differed as per the household requirement. The traditional three-walled, U-shaped mud stove served as a primary cook stove, used majorly for meal cooking; while the peripheral needs, such as preparation of cattle feed, heating of water, or space heating activities were met through the top-loading portable secondary cook stove. PM monitoring was done to encompass the entire cooking cycle to carefully evaluate PM concentrations in the kitchens area during and post cooking hours. Our study found high concentrations of PM in the semi-open kitchen of the representative household due to ineffective dispersion of combustion particles owing to poor ventilation near the cook stove area. During indoor monitoring, highest PM levels (426.6 μg/m3) were recorded while cooking with ‘mixed’ biomass fuel. The condition worsened during cooking with firewood as the PM10 levels reached as high as 793 μg/m3. In contrast, the average PM concentration was 75.4 μg/m3 in kitchen areas during LPG based cooking. The trend of PM concentration during cooking hours was found to be in the order firewood > dungcakes > crop residue > LPG. The trend was found to be consistent with the ‘fuel/energy stacking’ concept that depicts the primitive biomass-based fuels at the bottom of the ladder, and the advanced, clean and energy efficient fuel like LPG at the upper end of the ladder. Additionally, the EDX analysis showed a very high carbon content in case of biomass-based cooking fuel, suggesting incomplete combustion of fuel during the cooking process.

The average exposure assessed using the average daily dose (ADD) and lifetime average daily dose (LADD) estimation (based on time-activity recall and PM concentration) revealed that the lifetime average dose of cooking with firewood (18.16 μg/kg-day) is 13 times more than LPG based cooking (1.36 μg/kg-day). The risk of exposure to high PM concentrations in a poorly ventilated kitchen is, therefore, multifold to the main household cook. Daily cooking using biomass-based fuels have been linked with reduced lung function and susceptibility to other respiratory diseases. Although, LPG connections were installed in the households for primary cooking requirements, it was observed that around 33% of the households still used LPG in combination with solid biomass fuels due to budget constraints. Our study highlights the gender disparity in rural communities, limiting women to household chores, leading to diminution of income generating prospects for them. In a lifetime, women spent almost 50 years of their lives involved in cooking and related activities, starting at 15 years and continuing to work till 65 years of age. Especially for the chief cook (23 to <40), these years were the most vulnerable as the maximum burden of household cooking was upon them. These critical years contributed to the respiratory health and the overall quality of life among women.

The household geometry also contributed to the high dose in the kitchen area as minimal ventilation occurs in the semi-open kitchen and the location of the traditional stove seldom permitted the escape of emissions. The cooking area lacked ventilation through either air shaft/chimney or nearby windows. Moreover, the placement of the cookstove was such that the maximum amount of emissions released in the kitchen dispersed slowly into the living area, increasing the vulnerability of the other household members. Accordingly, the fractional deposition of soot particles in the airways increased as we moved down the household energy ladder. The total deposition was highest while using dung cakes (0.1563), followed by firewood (0.1427) and crop residue (0.1316). Also, a higher risk of respiratory illness among biomass users was evident due to increased deposition leading to reduced pulmonary function. The spirometry results showed abnormal ventilatory function in biomass users indicating lowered lung capacity owing to airway obstruction due to prolonged exposures. Overall extensive use of biomass in the study region had put 78.94% of the population at risk due to lower pulmonary function ensuing from daily smoke exposure. This work sets a precedent for future studies in the field of rural health impact assessment. Moreover, the study embodies the household air pollution profile and represents the household energy system in rural settings of Rajasthan. Further, the findings of this thesis set a paradigm for geographical evidence of cooking fuel problems and solutions in Karauli, Rajasthan and could serve as a primary record for the development of regional exposure inventory and interventional schemes. To comprehend the rural household intricacies, further cogitation is required to highlight the centrality of external factors in the household energy system.

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