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Remarkable nucleation and growth of ultrafine particles from vehicular exhaust

Guo, Song and Hu, Min and Peng, Jianfei and Wu, Zhijun and Zamora, Misti L. and Shang, Dongjie and Du, Zhuofei and Zheng, Jing and Fang, Xin and Tang, Rongzhi and Wu, Yusheng and Zeng, Limin and Shuai, Shijin and Zhang, Wenbin and Wang, Yuan and Ji, Yuemeng and Li, Yixin and Zhang, Annie L. and Wang, Weigang and Zhang, Fang and Zhao, Jiayun and Gong, Xiaoli and Wang, Chunyu and Molina, Mario J. and Zhang, Renyi (2020) Remarkable nucleation and growth of ultrafine particles from vehicular exhaust. Proceedings of the National Academy of Sciences of the United States of America, 117 (7). pp. 3427-3432. ISSN 0027-8424. PMCID PMC7035480. https://resolver.caltech.edu/CaltechAUTHORS:20200204-080030144

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Abstract

High levels of ultrafine particles (UFPs; diameter of less than 50 nm) are frequently produced from new particle formation under urban conditions, with profound implications on human health, weather, and climate. However, the fundamental mechanisms of new particle formation remain elusive, and few experimental studies have realistically replicated the relevant atmospheric conditions. Previous experimental studies simulated oxidation of one compound or a mixture of a few compounds, and extrapolation of the laboratory results to chemically complex air was uncertain. Here, we show striking formation of UFPs in urban air from combining ambient and chamber measurements. By capturing the ambient conditions (i.e., temperature, relative humidity, sunlight, and the types and abundances of chemical species), we elucidate the roles of existing particles, photochemistry, and synergy of multipollutants in new particle formation. Aerosol nucleation in urban air is limited by existing particles but negligibly by nitrogen oxides. Photooxidation of vehicular exhaust yields abundant precursors, and organics, rather than sulfuric acid or base species, dominate formation of UFPs under urban conditions. Recognition of this source of UFPs is essential to assessing their impacts and developing mitigation policies. Our results imply that reduction of primary particles or removal of existing particles without simultaneously limiting organics from automobile emissions is ineffective and can even exacerbate this problem.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1073/pnas.1916366117DOIArticle
https://www.pnas.org/content/suppl/2020/01/28/1916366117.DCSupplementalPublisherSupporting Information
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7035480PubMed CentralArticle
ORCID:
AuthorORCID
Wang, Yuan0000-0001-6657-8401
Wang, Weigang0000-0001-6911-1110
Molina, Mario J.0000-0003-2339-3225
Zhang, Renyi0000-0001-8708-3862
Additional Information:© 2020 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND). Contributed by Mario J. Molina, December 19, 2019 (sent for review September 23, 2019; reviewed by Robert L. McGraw and Fangqun Yu). PNAS first published February 3, 2020. This work was supported by National Natural Science Foundation of China Grants 91544214 and 21677002; National Key Research and Development Program of China Grant 2016YFC0202000: Task 3; National Research Program for Key Issues in Air Pollution Control Grant DQGG0103; and Robert A. Welch Foundation Grant A-1417. We thank Don Collins for the application of the QUALITY chamber. Data and Materials Availability: All data are available in the text or SI Appendix. S.G., M.H., J.P., and M.L.Z. contributed equally to this work. Author contributions: S.G., M.H., and R.Z. designed research; S.G., M.H., J.P., Z.W., M.L.Z., D.S., Z.D., J. Zheng, X.F., R.T., Y.W., S.S., W.Z., Y.W., Y.J., Y.L., W.W., F.Z., J. Zhao, X.G., C.W., and R.Z. performed research; S.S., M.J.M., and R.Z. contributed new reagents/analytic tools; S.G., M.H., J.P., Z.W., M.L.Z., L.Z., S.S., Y.W., A.L.Z., M.J.M., and R.Z. analyzed data; and S.G., M.H., A.L.Z., and R.Z. wrote the paper. Reviewers: R.L.M., Brookhaven National Laboratory; and F.Y., State University of New York at Albany. The authors declare no competing interest.
Funders:
Funding AgencyGrant Number
National Natural Science Foundation of China91544214
National Natural Science Foundation of China21677002
National Key Research and Development Program of China2016YFC0202000
National Research Program for Key Issues in Air Pollution ControlDQGG0103
Robert A. Welch FoundationA-1417
Subject Keywords:new particle formation; nucleation; ultrafine particles; growth; organics
Issue or Number:7
PubMed Central ID:PMC7035480
Record Number:CaltechAUTHORS:20200204-080030144
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200204-080030144
Official Citation:Remarkable nucleation and growth of ultrafine particles from vehicular exhaust. Song Guo, Min Hu, Jianfei Peng, Zhijun Wu, Misti L. Zamora, Dongjie Shang, Zhuofei Du, Jing Zheng, Xin Fang, Rongzhi Tang, Yusheng Wu, Limin Zeng, Shijin Shuai, Wenbin Zhang, Yuan Wang, Yuemeng Ji, Yixin Li, Annie L. Zhang, Weigang Wang, Fang Zhang, Jiayun Zhao, Xiaoli Gong, Chunyu Wang, Mario J. Molina, Renyi Zhang. Proceedings of the National Academy of Sciences Feb 2020, 117 (7) 3427-3432; DOI: 10.1073/pnas.1916366117
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101098
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:04 Feb 2020 17:26
Last Modified:03 Mar 2020 18:24

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