Assessing the impact of urban form and urbanization process on tropospheric nitrogen dioxide pollution in the Yangtze River Delta, China

Yuanyun Gao; Shuntian Wang; Chengxin Zhang; Chengzhi Xing; Wei Tan; Hongyu Wu; Xinhan Niu; Cheng Liu

doi:10.1016/j.envpol.2023.122436

Assessing the impact of urban form and urbanization process on tropospheric nitrogen dioxide pollution in the Yangtze River Delta, China

Environ Pollut. 2023 Nov 1:336:122436. doi: 10.1016/j.envpol.2023.122436. Epub 2023 Aug 26.

Authors

Yuanyun Gao¹, Shuntian Wang², Chengxin Zhang³, Chengzhi Xing⁴, Wei Tan⁴, Hongyu Wu⁵, Xinhan Niu⁶, Cheng Liu⁷

Affiliations

¹ Key Laboratory of Environmental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China; Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026, China; Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment of China, 8 Jiang Wang Miao St., Nanjing 210042, China.
² Department of Civil, Environmental and Geomatic Engineering, Institute of Environmental Engineering, Ecological Systems Design, Swiss Federal Institute of Technology, ETH Zurich, 8093 Zurich, Switzerland; Department of Humanities, Social, And Political Sciences, Institute of Science, Technology, And Policy (ISTP), Swiss Federal Institute of Technology, ETH Zurich, 8092 Zurich, Switzerland.
³ Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026, China. Electronic address: zcx2011@ustc.edu.cn.
⁴ Key Laboratory of Environmental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China.
⁵ School of Environmental Science and Optoelectronic Technology, University of Science and Technology of China, Hefei 230026, China.
⁶ Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026, China.
⁷ Key Laboratory of Environmental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China; Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026, China.

PMID: 37640224
DOI: 10.1016/j.envpol.2023.122436

Abstract

Optimizing urban form through urban planning and management policies can improve air quality and transition to demand-side control. Nitrogen dioxide (NO₂) in the urban atmosphere, mainly emitted by anthropogenic sources such as industry and vehicles, is a key precursor of fine particles and ozone pollution. Both NO₂ and its secondary pollutants pose health risks for humans. Here we assess the interactions between urban forms and airborne NO₂ pollution in different cities with various stages of urbanization in the Yangtze River Delta (YRD) in China, by using the machine learning and geographical regression model. The results reveal a strong correlation between urban fragmentation and tropospheric NO₂ vertical column density (TVCD) in YRD cities in 2020, particularly those with lower or higher levels of urbanization. The correlation coefficients (R²) between NO₂ TVCD and the largest patch index (a metric of urban fragmentation) in different cities are greater than 0.8. For cities at other urbanization stages, population and road density are strongly correlated with NO₂ TVCD, with an R² larger than 0.61. This study highlights the interdependence among urbanization, urban forms, and air pollution, emphasizing the importance of customized urban landscape management strategies for mitigating urban air pollution.

Keywords: Air pollution; Nitrogen dioxide; Urban form; Urbanization.