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Published May 27, 2015 | metadata_only
Journal Article

Formation of Urban Fine Particulate Matter


Urban air pollution represents one of the greatest environmental challenges facing mankind in the 21st century. Noticeably, many developing countries, such as China and India, have experienced severe air pollution because of their fast-developing economy and urbanization. Globally, the urbanization trend is projected to continue: 70% of the world population will reside in urban centers by 2050, and there will exist 41 megacities (with more than 10 million inhabitants) by 2030. Air pollutants consist of a complex combination of gases and particulate matter (PM). In particular, fine PM (particles with the aerodynamic diameter smaller than 2.5 μm or PM_(2.5)) profoundly impacts human health, visibility, the ecosystem, the weather, and the climate, and these PM effects are largely dependent on the aerosol properties, including the number concentration, size, and chemical composition. PM is emitted directly into the atmosphere (primary) or formed in the atmosphere through gas-to-particle conversion (secondary) (Figure 1). Also, primary and secondary PM undergoes chemical and physical transformations and is subjected to transport, cloud processing, and removal from the atmosphere.

Additional Information

© 2015 American Chemical Society. Received: February 2, 2015. Special Issue: 2015 Chemistry in Climate. This work was supported by the Robert A. Welch Foundation (Grant A-1417), the Ministry of Science and Technology of China (Grant 2013CB955800), a collaborative research program by Texas A&M University and the National Natural Science Foundation of China, and a Texas A&M University–Weizmann Collaborative Program. G.W. acknowledged the National Natural Science Foundation of China and the Strategic Priority Research Program of the Chinese Academy of Sciences for financial support (Grants 41325014, XDA05100103, and XDB05020401). W.W. acknowledged financial support for the Visiting Scholar Program by the Chinese Academy of Science and the National Natural Science Foundation of China (Grant 41227805). M.H. was supported by the National Basic Research Program, China Ministry of Science and Technology (Grant 2013CB228503), and National Natural Science Foundation of China (21190052). Y.W. was supported by the NASA ROSES10-COUND program. We were grateful to Professor A. R. Ravishankara of Colorado State University, Professor of Robert D. Kuchta of University of Colorado at Boulder, and Dr. Sasha Madronich of NCAR for helpful suggestions and discussions. The authors declare no competing financial interest.

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August 20, 2023
August 20, 2023