Household air pollution contributes substantially to ambient air pollution. Estimates of this contribution range between approximately 20 and 50% globally, with large spatial heterogeneity both between and within countries. Regardless of this heterogeneity — both in the prevalence of solid fuel use and in the estimates of household contributions to ambient air pollution — reducing household air pollution from solid fuel use has benefits across scales — it benefits people in homes who rely on these fuels, but also provides benefits to communities and airsheds by reducing ambient air pollution levels. Our work has focused on both top-down and bottom-up estimates of this contribution and the potential health implications of the contribution. Finally, with a group of global collaborators, we have estimated benefits associated with potential policy pathways to reduce household air pollution.

With Manish Desai, Krishnendu Mukhopadhyay, Naveen Puttaswamy, Sankar Sambandam, Gurusamy Thangavel, and Kalpana Balakrishnan.

The world’s most ambitious scale up of clean fuels has taken place across India in the past five years. The Pradhan Mantri Ujjwala Yojana (PMUY) program, building upon previous efforts, provided access to LPG for an additional 80 million homes. However, continued fuel stacking and inconsistent coverage of the intervention has left overall household air pollution exposure reductions in households and associated ambient air pollution reductions lower than what is needed to meet Indian national standards or WHO guidelines. Several recent modelling exercises suggest that household biomass burning results in significant contributions to ambient air pollution at national and regional levels. However, there is almost no actual data to support quantitative targets for program design and maintenance at the village and district level that could guide village coverage goals for household use of LPG to displace solid fuel burning. Because of the PMUY scale up history, patchy uptake at community levels, and relatively low level of industrial sources of pollution, Southern India provides an ideal setting to study the Reach and Effectiveness of this massive LPG program and to contribute evidence-based guidance to support critical implementation targets for policy around village- level coverage and LPG utilization.

This research quantifies the contribution of households to ambient air pollution in North India by (1) updating and improving existing emissions inventories through activity-based modeling at high temporal and spatial resolution, (2) providing field-based emissions of SVOCs and other ozone precursors to, for the first time, model the contribution of household air pollution to regional secondary particle formation; and (3) monitoring rural ambient and near-home concentrations of and personal exposures to PM2.5. Modeling efforts will enable manipulation of various sources and emission rates, across a variety of relevant policy scenarios, enabling estimation of how certain initiatives may impact air pollution at varying scales.

This project leverages a multi-year collaboration between University of California Berkeley and INCLEN, the International Clinical Epidemiology Network (New Delhi, India). INCLEN runs a large demographic and environmental surveillance site ~75 kilometers south of Delhi; their activities span over 50 villages covering approximately 200,000 individuals. While relatively close to Delhi, most households in the area rely on brushwood and dung as primary household fuels. The entire region is prone to low, ground-level inversions in the winter, resulting in especially high PM concentrations between November and February.

Study findings have been disseminated to local stakeholders, policy makers, members of relevant ministries, environmental health practitioners, and other researchers through journal articles.