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This study investigated the AQI (air quality index) and atmospheric pollutants including PM 2.5 , PM 10 , CO, SO 2 , NO 2 and O 3 in Chongqing, Luzhou and Chengdu from 2017 to 2019. In addition, the impacts of the COVID-19 event on the air quality in the three cities in 2020 were compared and discussed. For the combined AQIs for the three cities, in spring, the daily AQIs ranged between 25 and 182 and averaged 72.1. In summer, the daily AQIs ranged between 24 and 206 and averaged 77.5. In autumn, the daily AQIs ranged between 22 and 170 and averaged 61.1, and in winter, the daily AQIs ranged between 28 and 375 and averaged 99.6. The distributions of the six AQI classes in spring were 3%, 94%, 3%, 0%, 0%, and 0%; in summer, they were 11%, 74%, 15%, 0%, 0% and 0%; in autumn, they were 29%, 70%, 1%, 0%, 0%, and 0%, and in winter, they were 1%, 52%, 44%, 3%, 0%, and 0%, respectively. The average AQIs, in order, were Chengdu (85.4) > Chongqing (73.8) > Luzhou (73.2). Both the highest AQIs and PM 2.5 (as the major indicatory air pollutant) occurred mainly in the low temperature season (January, December, and February), while O 3 was the main air pollutant in June and August when the weather was hot. In February 2020, during the epidemic prevention and control actions taken in response to COVID-19 for the three cities, the combined AQIs for the top five days with the highest

A radio frequency (RF) plasma system used to decompose trifluoromethane (CHF 3 or HFC-23) is demonstrated. The CHF 3 decomposition fractions (η CHF 3 ) and mole fractions of detected products in the effluent gas streams of CHF 3 /O 2 /Ar and CHF 3 /H 2 /Ar plasma systems, respectively, have been determined. The effects of four experimental parameters, input power, O 2 /CHF 3 or H 2 / CHF 3 ratio, operational pressure, and the CHF 3 feeding concentration were investigated. The same species detected in the effluent gas streams of both CHF 3 /O 2 /Ar and CHF 3 /H 2 /Ar plasma systems were CH 2 F 2 , CF 4 , HF, and SiF 4 . However, the CO 2 and COF 2 were detected only in the CHF 3 /O 2 /Ar plasma system and the CH 4 , C 2 H 2 , and CH 3 F were detected only in the CHF 3 /H 2 / Ar plasma system. The results of a model sensitivity analysis showed that the input power was the most influential parameter for η CHF 3 both in the CHF 3 /O 2 /Ar and CHF 3 /H 2 /Ar plasma systems. Furthermore, the possible reaction pathways were built up and elucidated in this study. The addition of hydrogen for CHF 3 decomposition can produce a significant amount of HF and the main carbonaceous byproducts were CH 4 and C 2 H 2 . Even though the η CHF 3 in the CHF 3 /H 2 /Ar plasma system is lower than that in the CHF 3 /O 2 /Ar plasma system, but due to the more advantages mentioned above, a hydrogen-based RF plasma system is a better alternative to decompose CHF 3 .