Comprehensive Emission Factors and Chemical Characterization of Indian Crop Residue Burning Emissions

Crop residue burning is a major source of air pollution over the Indo-Gangetic Plain in India and is becoming increasingly prevalent across the country. Initially restricted to wheat and rice, residue burning now extends to crops such as sugarcane, corn, millet, and others. The present study investigates emissions from the burning of these five major crop residues. Emission characterization includes the development of emission factors for gases (CO2, CO, SO2, NO, NO2, total hydrocarbons) and particulates (size-resolved particle number concentrations and PM2.5). In addition, PM2.5 was chemically characterized to derive emission factors for organic carbon, elemental carbon, water-soluble organic carbon, water-soluble inorganic ions, trace metals, water-soluble organic nitrogen, and PM2.5-bound polycyclic aromatic hydrocarbons. To better understand volatile organic compounds (VOCs) emission, untargeted analysis was performed using GC × GC-HR-TOF-MS, resolving approximately 367 chemical compounds across the five crop residue burning emissions. This study provides one of the most detailed and comprehensive emission characterizations of major Indian crop residues. The data set generated here is urgently needed not only by modelers to reduce uncertainties in regional and global air quality assessments but also by air pollution control researchers as primary input data to identify target VOCs and design, evaluate, and optimize mitigation and removal technologies.