Black carbon emissions from road transport in Karnataka, India: High-resolution inventory and mitigation strategies

Black carbon (BC) emissions from road transportation significantly impact air quality, public health, and climate change. This study presents a high-resolution (1 × 1 km) emissions inventory for Karnataka, India, offering a detailed assessment of key BC emission hotspots, major contributing vehicle categories, and projected trends under business-as-usual (BAU) and mitigation scenarios. It also evaluates economic costs, health benefits, and uncertainties to understand BC pollution from road transport. In 2022, Karnataka's Road Transport sector contributed 39.76 % of the state's total BC emissions, with Bengaluru Urban district recording the highest emissions of 0.87 Gg. Without intervention, projections indicate that heavy-duty vehicles (Trailers & Tractors and Trucks & Lorries) emissions could reach 158.89 and 102.72 metric tons (MT) by 2050, exacerbating environmental and health issues. Variable fuel consumption, diverse operations, and seasonal variations drive the high uncertainty (±31.05 %) in Trailers and Tractors. Transitioning from internal combustion (IC) two-wheelers to electric vehicles (EVs) could have economic benefits of ₹20.58 lakh per km/year by 2050, reducing fossil fuel dependence and emissions. Mitigating BC emissions could cut the health economic expenditure per person/km/year from ₹17,333.33 (BAU) to ₹263.70 by 2050. This dramatic reduction underscores the potential for improved public health, reduced healthcare costs, and enhanced overall well-being for Karnataka's population. Integrating BC reduction into air quality policies can curb emissions, improve health, and support climate goals. These findings support evidence-based policymaking and offer actionable insights into sustainable urban transport planning in Karnataka.