Climate Relevant Properties of Aerosol Emissions from Iron & Steel and Thermal Power Plant Emissions in India

Industrial and power plant emissions are among the major contributors to air pollution in India, accounting for 37% of atmospheric PM_2.5 emissions, with significant implications for climate change and human health. These emissions, primarily resulting from combustion processes, include carbonaceous aerosols such as particulate matter and light-absorbing carbon. The type of fuel used, the air pollution control technology implemented, and the industrial processes adopted heavily influence emissions from industrial sources. Aerosol optical properties, such as the mass absorption cross-section (MAC) and mass scattering coefficients (MSC), are critical for regional climate assessments. This study presents real-world measurements of MACs and MSCs from iron & steel, and thermal power plant emissions under Indian conditions. Stack emission measurements were conducted in real-world settings at iron and steel plants and thermal power plants, using the Versatile Source Sampling System (VS3). The VS3 system allowed a fraction of stack emissions to pass through an isokinetic particle sampling probe into a dilution tunnel, ensuring homogeneous mixing, negligible wall losses, and complete aerosol quenching. Dilution ratios of 20–60 with zero air simulated atmospheric dilution conditions. PM_2.5 mass was collected on various filter substrates for gravimetric and chemical analyses. Particle absorption and scattering were measured using an Aethalometer (AE33) and a Nephelometer (IN102), respectively, while the light-absorbing carbonaceous fraction of PM_2.5 was analysed on quartz filters using a thermal-optical reflectance analyser. PM_2.5 emission factors from iron & steel (sponge iron) and thermal power plants are 0.11 – 0.16 and 0.07 – 0.44 g/kg of fuel used respectively. MAC values (m²/g PM_2.5) were determined to range from 0.01 – 0.14 m²/g PM_2.5 for iron and steel plants and 0.03 – 0.29 m²/g PM_2.5 for thermal power plants. The EC, and OC emission factors and other optical properties including MSCs, AAE, and SSA will be discussed for these industries in the paper. Findings from this study have significant implications for climate assessments and the development of policies aimed at improving air quality, particularly for the major sources in the industrial sector.