Long-term source apportionment of PM2.5 across the contiguous United States (2000-2019) using a multilinear engine model

Qiao Zhu; Yang Liu; Sina Hasheminassab

doi:10.1016/j.jhazmat.2024.134550

Long-term source apportionment of PM_2.5 across the contiguous United States (2000-2019) using a multilinear engine model

J Hazard Mater. 2024 May 7:472:134550. doi: 10.1016/j.jhazmat.2024.134550. Online ahead of print.

Authors

Qiao Zhu¹, Yang Liu², Sina Hasheminassab³

Affiliations

¹ Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA.
² Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA. Electronic address: yang.liu@emory.edu.
³ Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.

PMID: 38728865
DOI: 10.1016/j.jhazmat.2024.134550

Abstract

Identifying PM_2.5 sources is crucial for effective air quality management and public health. This research used the Multilinear Engine (ME-2) model to analyze PM_2.5 from 515 EPA Chemical Speciation Network (CSN) and Interagency Monitoring of Protected Visual Environments (IMPROVE) sites across the U.S. from 2000 to 2019. The U.S. was divided into nine regions for detailed analysis. A total of seven source types (tracers) were resolved across the country: (1) Soil/Dust (Si, Al, Ca and Fe); (2) Vehicle emissions (EC, OC, Cu and Zn); (3) Biomass/wood burning (K); (4) Heavy oil/coal combustion (Ni, V, Cl and As); (5) Secondary sulfate (SO₄^2-); (6) Secondary nitrate (NO₃^-) and (7) Sea salt (Mg, Na, Cl and SO₄^2-). Furthermore, we extracted and calculated secondary organic aerosols (SOA) based on the secondary sulfate and nitrate factors. Notably, significant reductions in secondary sulfate, nitrate, and heavy oil/coal combustion emissions reflect recent cuts in fossil-fueled power sector emissions. A decline in SOA suggests effective mitigation of their formation conditions or precursors. Despite these improvements, vehicle emissions and biomass burning show no significant decrease, highlighting the need for focused control on these persistent pollution sources for future air quality management.

Keywords: Air quality policies; Emission reductions; Fossil fuel emissions; PM(2.5) source apportionment.