Trends in Global Black Carbon Emissions and Population Exposure from 1700 to 2021.

Black carbon (BC) emission inventories are essential tools for tackling the dual challenges of climate change and air pollution. However, uncertainties in source attribution, emission factors, and temporal-spatial variability often lead to biased BC emission inventories. By integrating recently published energy consumption data from residential and industrial sectors with field-measured emission factors, we developed a novel BC inventory with a high spatial resolution of 0.1°×0.1° on a monthly basis. This inventory highlights the evolution of BC from 1700 to 2021, spanning the preindustrial era to the present, providing a valuable tool for assessing human interventions in air pollution and climate. Indoor exposure is included for the first time. While ambient BC concentrations mirrored the emissions trend, indoor BC concentrations shifted in the opposite direction, driven by the transition from solid fuels to clean energy in the residential sector. Consequently, population exposure, predominantly influenced by indoor exposure, decreased from 29.7 (28.0-31.6) μg/m in 1700 to 8.8 (8.2-9.4) μg/m in 2021 on a global average. Females were exposed to higher BC levels than males due to spending more time in kitchens.