title: Global long-range transport and lung cancer risk from polycyclic aromatic hydrocarbons shielded by coatings of organic aerosol.
abstract: Polycyclic aromatic hydrocarbons (PAHs) have toxic impacts on humans and ecosystems. One of the most carcinogenic PAHs, benzo(a)pyrene (BaP), is efficiently bound to and transported with atmospheric particles. Laboratory measurements show that particle-bound BaP degrades in a few hours by heterogeneous reaction with ozone, yet field observations indicate BaP persists much longer in the atmosphere, and some previous chemical transport modeling studies have ignored heterogeneous oxidation of BaP to bring model predictions into better agreement with field observations. We attribute this unexplained discrepancy to the shielding of BaP from oxidation by coatings of viscous organic aerosol (OA). Accounting for this OA viscosity-dependent shielding, which varies with temperature and humidity, in a global climate/chemistry model brings model predictions into much better agreement with BaP measurements, and demonstrates stronger long-range transport, greater deposition fluxes, and substantially elevated lung cancer risk from PAHs. Model results indicate that the OA coating is more effective in shielding BaP in the middle/high latitudes compared with the tropics because of differences in OA properties (semisolid when cool/dry vs. liquid-like when warm/humid). Faster chemical degradation of BaP in the tropics leads to higher concentrations of BaP oxidation products over the tropics compared with higher latitudes. This study has profound implications demonstrating that OA strongly modulates the atmospheric persistence of PAHs and their cancer risks.
authors.affiliation: Pacific Northwest National Laboratory, Richland, WA 99352; ManishKumar.Shrivastava@pnnl.gov.
authors.forename: Manish
authors.identifier: 0000-0002-9053-2400
authors.initials: M
authors.lastname: Shrivastava
authors.affiliation: Pacific Northwest National Laboratory, Richland, WA 99352.
authors.forename: Sijia
authors.initials: S
authors.lastname: Lou
authors.affiliation: Pacific Northwest National Laboratory, Richland, WA 99352.
authors.forename: Alla
authors.initials: A
authors.lastname: Zelenyuk
authors.affiliation: Pacific Northwest National Laboratory, Richland, WA 99352.
authors.forename: Richard C
authors.initials: RC
authors.lastname: Easter
authors.affiliation: Pacific Northwest National Laboratory, Richland, WA 99352.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Corley
authors.affiliation: Pacific Northwest National Laboratory, Richland, WA 99352.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Thrall
authors.affiliation: Pacific Northwest National Laboratory, Richland, WA 99352.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Rasch
authors.affiliation: Pacific Northwest National Laboratory, Richland, WA 99352.
authors.forename: Jerome D
authors.initials: JD
authors.lastname: Fast
authors.affiliation: Department of Chemistry, Oregon State University, Corvallis, OR 97331.|Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97331.
authors.forename: Staci L
authors.initials: SL
authors.lastname: Massey Simonich
authors.affiliation: School of Civil & Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332.
authors.forename: Huizhong
authors.identifier: 0000-0003-1335-8477
authors.initials: H
authors.lastname: Shen
authors.affiliation: Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
authors.forename: Shu
authors.initials: S
authors.lastname: Tao
mesh_terms: D000336:Aerosols; D001272:Atmosphere / Q000737:chemistry*; D001564:Benzo(a)pyrene / Q000009:adverse effects / Q000737:chemistry*; D002273:Carcinogens / Q000737:chemistry*; D002980:Climate; D006801:Humans; D008175:Lung Neoplasms / Q000139:chemically induced*; D008956:Models, Chemical; D010084:Oxidation-Reduction; D018570:Risk Assessment
chemical_list: D000336:Aerosols; D002273:Carcinogens; D001564:Benzo(a)pyrene
keywords: climate model; heterogeneous chemistry; organic aerosols; polycyclic aromatic hydrocarbons; viscous aerosol shield