Identifying sources of black carbon associated with high mortality risk in Beijing, China based on long-term hourly...

Black carbon (BC) is an important air pollutant that poses serious risks to human health. However, previous studies have largely focused on total BC mass concentrations, while the health risks associated with source-specific BC remain poorly understood, limiting the development of effective health-oriented control strategies. To address this issue, long-term source-specific BC mortality analyses were conducted in Beijing during 2016-2019 by integrating an hourly-resolution dataset of 19 PM_2.5 components, Positive Matrix Factorization (PMF) source apportionment, and high-quality mortality records. The findings indicated that the health risk of BC could vary by source, with traffic BC posing the highest non-accidental mortality risk (RR: 1.014, 95% CI: 1.003, 1.025), followed by biomass burning and atmospherically aged BC. During the study period, the stringent coal control policies implemented in northern China led to a drastic reduction in coal BC concentration, accounting for 40% of the reduction in BC-attributable mortality burden. Consequently, the three non-coal sources (traffic, biomass burning, and aged BC) became the dominant contributors in 2019, collectively accounting for 86% of the BC-attributable mortality burden. These findings highlight substantial source-specific differences in BC mortality risks and provide evidence for developing health-oriented policies to better protect public health through clean air initiatives.