[Analysis of VOCs Emission Characteristics and Emission Reduction Potential of Typical Industries in Jinan, China].

Based on the air pollutant emission inventory of Jinan in 2020, the VOCs emission status and existing problems of typical industries including the chemical industry, industrial coating, printing, and furniture manufacturing were investigated and analyzed, and two emission reduction scenarios were designed to estimate the emission reduction potential according to the enterprise scales and the end-of-pipe treatment techniques. The results showed that the VOCs emissions of the typical industries from large to small were the chemical industry(7947.92 t), industrial coating(2383.29 t), printing(792.87 t), and furniture manufacturing(143.79 t). The chemical industry and industrial painting were dominated by large enterprises, accounting for 46.45% and 50.89% of VOCs emissions, whereas printing and furniture manufacturing were dominated by medium-sized enterprises, accounting for 51.76% and 42.37% of VOCs emissions, respectively. The end-of-pipe treatment was dominated by a single inefficient treatment technique, and the utilization rate of efficient treatment techniques such as combustion techniques and combination techniques was only 7.46%. The on-site investigation reported some problems in some enterprises, including incomplete source substitution, inadequate management of fugitive emissions, and unsuitable end-of-pipe treatment facilities. Therefore, VOCs emissions of typical industries had a certain reduction potential. Under the two designed emission reduction scenarios, the chemical industry had the greatest emission reduction potential, with emission reduction rates of 69.58%-84.99%, and the emission reduction rates of industrial coating, printing, and furniture manufacturing industries were 26.98%-34.74%, 36.96%-59.74%, and 8.55%-40.45%, respectively. Among the four industries, large and medium-sized enterprises had greater emission reduction potential, with average emission reduction rates of 70.00% and 44.23%, respectively. Under the scenario of a higher emission reduction target, the average emission reduction rates of small and micro enterprises were greatly increased, reaching 87.49% and 79.65%, respectively. The results of this study could provide scientific basis for developing VOCs governance in typical industries and enterprises.

Analysis of Factors Influencing Air Quality in Different Periods during COVID-19: A Case Study of Tangshan, China.

This study aimed to analyze the main factors influencing air quality in Tangshan during COVID-19, covering three different periods: the COVID-19 period, the Level I response period, and the Spring Festival period. Comparative analysis and the difference-in-differences (DID) method were used to explore differences in air quality between different stages of the epidemic and different years. During the COVID-19 period, the air quality index (AQI) and the concentrations of six conventional air pollutants (PM2.5, PM10, SO2, NO2, CO, and O3-8h) decreased significantly compared to 2017-2019. For the Level I response period, the reduction in AQI caused by COVID-19 control measures were 29.07%, 31.43%, and 20.04% in February, March, and April of 2020, respectively. During the Spring Festival, the concentrations of the six pollutants were significantly higher than those in 2019 and 2021, which may be related to heavy pollution events caused by unfavorable meteorological conditions and regional transport. As for the further improvement in air quality, it is necessary to take strict measures to prevent and control air pollution while paying attention to meteorological factors.

[Impacts of COVID-19 Lockdown on Air Quality in Shenzhen in Spring 2022].

The short-term reduction of air pollutant emissions is an important emergency control measure for avoiding air pollution exceedances in Chinese cities. However, the impacts of short-term emission reductions on the air qualities in southern Chinese cities in spring has not been fully explored. We analyzed the changes in air quality in Shenzhen, Guangdong before, during, and after a city-wide lockdown associated with COVID-19 control during March 14 to 20, 2022. Stable weather conditions prevailed before and during the lockdown, such that local air pollution was strongly affected by local emissions. In-situ measurements and WRF-GC simulations over the Pearl River Delta (PRD) both showed that, due to reductions in traffic emissions during the lockdown, the concentrations of nitrogen dioxide (NO2), respirable particulate matter (PM10), and fine particulate matters (PM2.5) in Shenzhen decreased by (-26±9.5)%, (-28±6.4)%, and (-20±8.2)%, respectively. However, surface ozone (O3) concentration did not change significantly[(-1.0±6.5)%]. TROPOMI satellite observations of formaldehyde and nitrogen dioxide column concentrations indicated that the ozone photochemistry in the PRD in spring 2022 was mainly controlled by the volatile organic compound (VOCs) concentrations and was not sensitive to the reduction in nitrogen oxide (NOx) concentrations. Reduction in NOx may even have increased O3, because the titration of O3 by NOx was weakened. Due to the small spatial-temporal extent of emission reductions, the air quality effects caused by this short-term urban-scale lockdown were weaker than the air quality effects across China during the widespread COVID-19 lockdown in 2020. Future air quality management in South China cities should consider the impacts of NOx emission reduction on ozone and focus on the co-reduction scenarios of NOx and VOCs.