Document Type

Article

Publication Date

12-2-2025

Abstract

Abstract

The global phase-out of leaded gasoline marked a major milestone in pollution control, yet modern uses of lead (Pb) continue to pose significant health risks, especially in low- and middle-income countries. In the Philippines, significant data gaps still exist despite increasing exposure. This study presents to the best of our knowledge, the first Pb isotopic fingerprinting of atmospheric aerosols in Metro Manila, Philippines, covering fine (0.56–1 μm) and coarse (5.6–10 μm) fractions, collected in 2018–2019. Results show that local sources, mainly industrial activities (45–62 %) and fossil fuel combustion (30–45 %), are now the dominant contributors to airborne Pb, while a minor legacy leaded gasoline and geogenic Pb persists (< 18 %) through soil resuspension. Stable isotopes show no clear seasonal pattern. Together with 25 fold higher Pb concentration in the fine fraction, these indicate limited transboundary input. Regional comparison highlights overlapping Pb isotopic composition across Southeast Asia, but is distinct from areas farther north due to intensive coal use in China. The consistency between isotopic fingerprinting and Positive Matrix Factorization (PMF) results demonstrates the value of combining methods for robust source apportionment. These findings demonstrate the continuing importance of isotopic monitoring for distinguishing contemporary and legacy Pb sources and informing targeted air quality management in rapidly developing regions.

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