Atmos. Chem. Phys., 18, 8017–8039, 2018 https://doi.org/10.5194/acp-18-8017-2018 © Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. Source influence on emission pathways and ambient PM2:5 pollution over India (2015–2050) Chandra Venkataraman1,2, Michael Brauer3, Kushal Tibrewal2, Pankaj Sadavarte2,4, Qiao Ma5, Aaron Cohen6, Sreelekha Chaliyakunnel7, Joseph Frostad8, Zbigniew Klimont9, Randall V. Martin10, Dylan B. Millet7, Sajeev Philip10,11, Katherine Walker6, and Shuxiao Wang5,12 1Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, India 2Interdisciplinary program in Climate Studies, Indian Institute of Technology Bombay, Powai, Mumbai, India 3School of Population and Public Health, The University of British Columbia, Vancouver, British Columbia V6T1Z3, Canada 4Institute for Advanced Sustainability Studies (IASS), Berliner Str. 130, 14467 Potsdam, Germany 5State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China 6Health Effects Institute, Boston, MA 02110, USA 7Department of Soil, Water, and Climate, University of Minnesota, Minneapolis–Saint Paul, MN 55108, USA 8Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA 98195, USA 9International Institute for Applied Systems Analysis, Laxenburg, Austria 10Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada 11NASA Ames Research Center, Moffett Field, California, USA 12State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing 100084, China Correspondence: Chandra Venkataraman ([email protected]) Received: 1 December 2017 – Discussion started: 13 December 2017 Revised: 10 April 2018 – Accepted: 15 May 2018 – Published: 7 June 2018 Abstract. India is currently experiencing degraded air qual- tors, while the remainder are from “other” sources, wind- ity, and future economic development will lead to challenges blown dust and extra-regional sources. Leading contributors for air quality management. Scenarios of sectoral emissions are residential biomass combustion, power plant and indus- of fine particulate matter and its precursors were developed trial coal combustion and anthropogenic dust (including coal and evaluated for 2015–2050, under specific pathways of fly ash, fugitive road dust and waste burning). Transportation, diffusion of cleaner and more energy-efficient technologies. brick production and distributed diesel were other contribu- The impacts of individual source sectors on PM2:5 concentra- tors to PM2:5. Future evolution of emissions under regula- tions were assessed through systematic simulations of spa- tions set at current levels and promulgated levels caused fur- tially and temporally resolved particulate matter concentra- ther deterioration of air quality in 2030 and 2050. Under an tions, using the GEOS-Chem model, followed by population- ambitious prospective policy scenario, promoting very large weighted aggregation to national and state levels. We find shifts away from traditional biomass technologies and coal- that PM2:5 pollution is a pan-India problem, with a regional based electricity generation, significant reductions in PM2:5 character, and is not limited to urban areas or megacities. levels are achievable in 2030 and 2050. Effective mitigation Under present-day emissions, levels in most states exceeded of future air pollution in India requires adoption of aggres- −3 the national PM2:5 annual standard (40 µg m ). Sources re- sive prospective regulation, currently not formulated, for a lated to human activities were responsible for the largest three-pronged switch away from (i) biomass-fuelled tradi- proportion of the present-day population exposure to PM2:5 tional technologies, (ii) industrial coal-burning and (iii) open in India. About 60 % of India’s mean population-weighted burning of agricultural residue. Future air pollution is dom- PM2:5 concentrations come from anthropogenic source sec- inated by industrial process emissions, reflecting larger ex- Published by Copernicus Publications on behalf of the European Geosciences Union. 8018 C. Venkataraman et al.: Source influence on emission pathways and ambient PM2:5 pollution pansion in industrial, rather than residential energy demand. pact human mortalities and life expectancy. To extend the un- However, even under the most active reductions envisioned, derstanding of ambient air pollution to multiple (regional and the 2050 mean exposure, excluding any impact from wind- national) scales, for multiple pollutants, methods which com- blown mineral dust, is estimated to be nearly 3 times higher bine chemical transport modelling with data from satellite re- than the WHO Air Quality Guideline. trievals combined with available monitoring data have been developed (van Donkelaar et al., 2010; Brauer et al., 2012, 2016; Dey et al., 2012; Shaddick et al., 2018) and can be used to evaluate current levels and trends. The latest Global 1 Introduction Burden of Disease (GBD) 2015 estimates indicate that the population-weighted mean PM2:5 concentration for India as India hosts the world’s second largest population (UNDP, a whole was 74.3 µg m−3 in 2015, up from about 60 µg m−3 2017), but accounts for only 6 % of the world’s total primary in 1990 (Cohen et al., 2017). At current levels, 99.9 % of energy use (IEA, 2015). However, India is an emerging econ- the Indian population is estimated to live in areas where the omy with significant growth in a multitude of energy-use ac- World Health Organization (WHO) Air Quality Guideline of tivities in industry and transport sectors, as well as in resi- 10 µg m−3 was exceeded. Nearly 90 % of people lived in ar- dential, agricultural and informal industry sectors (Sadavarte eas exceeding the WHO Interim Target 1 of 35 µg m−3. and Venkataraman, 2014; Pandey et al., 2014). With expan- Strategies for mitigation of air pollution require un- sion in power generation (CEA, 2016) and industrial pro- derstanding of pollutant emissions, differentiated by emit- duction (Planning Commission, Government of India, 2013), ting sectors and by sub-national regions, representing both emissions from these sectors were estimated to have in- present-day conditions and future evolution under different creased about 2-fold between 1995 and 2015 (Sadavarte and pathways of growth and technology change. Future projec- Venkataraman, 2014). There is a steady demand for motor- tions of emissions, for climate relevant species, are available ized vehicles for both personal and public transport, with an in the representative concentration pathway (RCP) scenar- increase in ownership of motorized two-wheeler motorcycles ios (Fujino et al., 2006; Clarke et al., 2007; van Vuuren et and scooters and four-wheeler cars (MoRTH, 2012), in both al., 2007; Riahi et al., 2007; Hijioka et al., 2008), more re- rural and urban areas. Traditional technologies, and the use cently for the Shared Socioeconomic Pathway (SSP) scenar- of solid biomass fuels, are widespread in the residential sec- ios (Riahi et al., 2017; Rao et al., 2017), while primary PM2:5 tor (cooking with biomass fuel cook stoves and lighting with is included in inventories like ECLIPSE (Klimont et al., kerosene wick lamps), the agricultural sector (open burning 2017, 2018). Inventories developed for HTAP_v2 (Janssens- of agricultural residue for field clearing) and the informal in- Maenhout et al., 2015) address emissions of a suite of pol- dustry sector (brick production, processing of food and agri- lutants for 2008 and 2010. These scenarios and emission cultural products). Ambient PM2:5 (particulate matter in a datasets are developed through globally consistent method- size fraction with aerodynamic diameter smaller than 2.5 µm) ologies, leaving room for refinement through more detailed concentrations are influenced by emissions of both primary regional studies. Thus, in this work we develop and evaluate or directly emitted PM2:5, and its precursor gases, includ- sectoral emission scenarios of fine particulate matter and its ing SO2, NH3, NOx and NMVOCs (non-methane volatile precursors and constituents from India, during 2015–2050, organic compounds), whose atmospheric reactions yield sec- under specific pathways of diffusion of cleaner and more ondary particulate sulfate, nitrate and organic carbon, while energy-efficient technologies. The work is broadly related to reactions of NOx and NMVOCs also increase ozone levels. HTAP scientific questions including understanding of (i) sen- Ozone precursor gases and particulate black carbon and or- sitivity of regional PM2:5 pollution levels to magnitudes of ganic carbon (BC and OC) are identified in the list of short- emissions from source sectors and (ii) changes in PM2:5 lev- lived climate pollutants or SLCPs (CCAC, 2014). els as a result of expected, as well as ambitious, air pollu- Air quality is a public health issue of concern in India. Ac- tion and climate change abatement efforts. The impacts of cording to the World Health Organization (WHO), 37 cities individual source sectors on PM2:5 concentrations is assessed from India feature in a global list of 100 world cities with the through simulation of spatially and temporally resolved par- highest PM10 (PM with aerodynamic diameter < 10 µm) pol- ticulate matter concentrations, using the GEOS-Chem chem- lution, with cities like Delhi, Raipur, Gwalior and Lucknow ical transport model,