**1. Introduction**

China's energy consumption has increased rapidly, and urban air environment problems have become increasingly prominent in recent years. Tropospheric ozone (O3) has become one of the main pollutants affecting air quality. Volatile organic compounds (VOCs) have attracted widespread attention as important precursors of O3. VOCs refer to a class of organic gas compounds that exist in the air, including alkanes, aromatic hydrocarbons, olefins, halogenated hydrocarbons, and oxygenated hydrocarbons [1,2]. Extensive participation in atmospheric photochemical reactions leads to the formation of ozone and secondary organic aerosols (SOAs), which have a strong risk of carcinogenicity, which

**Citation:** Shi, J.; Bao, Y.; Xiang, F.; Wang, Z.; Ren, L.; Pang, X.; Wang, J.; Han, X.; Ning, P. Pollution Characteristics and Health Risk Assessment of VOCs in Jinghong. *Atmosphere* **2022**, *13*, 613. https:// doi.org/10.3390/atmos13040613

Academic Editors: Duanyang Liu, Honglei Wang and Kai Qin

Received: 3 March 2022 Accepted: 6 April 2022 Published: 11 April 2022

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is harmful to ambient air quality and human health [3,4]. Health brings threats such as respiratory damage, teratogenicity, and carcinogenicity [5,6].

Presently, various countries in the world have carried out VOCs-related research. China's research is mainly concentrated in the Beijing-Tianjin-Hebei and surrounding areas [7–10], Yangtze River Delta [11–13], Pearl River Delta [14–16], and other economically developed and densely populated areas of urban agglomerations, using offline or online monitoring analysis instruments and analysis methods to conduct related research. For example, Jay used proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) to perform highly time-resolved measurements in Beijing to study the characteristics and sources of volatile organic compounds (VOCs) [7]. Wei and Wang studied Handan, Hebei Province, a typical industrialized city in China; they conducted online measurements of VOCs and discussed their impact on PM2.5 in the atmosphere [8,9]. Gu analyzed the multiscale chemical characterization and source apportionment of volatile organic compounds (VOCs) in Tianjin, China, from 1 November 2018 to 15 March 2019 [10]. Wang conducted online measurements of VOCs in Nanjing during the epidemic and evaluated the impact of the COVID-19 lockdown on the mixing ratio and sources of VOCs [12]. Ma investigated the pollution characteristics of VOCs products from eight synthetic resin enterprises in Shanghai, China [13]. Wang conducted a field study on the specific VOC (including OVOC) emissions of six construction machinery and five inland ships in the Pearl River Delta (PRD) region [14].

Relatively less attention has been paid to the atmospheric environment in southwest China, especially in the border cities affected by Southeast and South Asia. Jinghong city is located in the south of Yunnan province, close to Myanmar, Laos, and other countries, with the characteristics of a tropical climate and dense vegetation. It is restricted by the natural geographical conditions of typical basin topography, less precipitation, high temperature, and more inversion weather in winter and low winds. Village units and residential edges have frequent straw and waste incineration, as well as downtown restaurants and barbecue stalls with no pollution control facilities. Surrounding the city, rubber and wood processing factories produce waste gases. Combined with this, vehicle use has risen in recent years; all of the above release emissions of nitrogen oxides (NOx) and VOCs into the city and increase the production of ozone. Ozone is a secondary photochemical pollutant and greenhouse gas. It is formed by the reaction of NOx and VOCs, and other precursors under highintensity ultraviolet light. Favorable conditions for ozone generation are mainly found in suburban areas, where NOx-rich air from windward urban agglomerations mix with VOCs emitted by trees and at high altitudes due to enhanced UV radiation [17]. Phytotoxic ozone has caused significant damage to terrestrial vegetation worldwide [18]. Dry deposition on plant surfaces (cuticle, bark), soil and stagnant water, and deposition through stomata into leaves leads to oxidative damage, which is the cause of carbon dioxide absorption in photosynthesis and decreased forest productivity [19,20].

In this study, VOCs, an important precursor of ozone, were taken as the research object, as well as VOC species concentration, ozone formation potentials, and health risks and sources. These were studied to provide a scientific basis for VOCs and ozone pollution control in this region.
