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Online volatile organic compounds (VOCs) were continuous monitored before and after the Omicron policy change at an urban site in polluted Zhengzhou from December 1, 2022, to January 31, 2023. The characteristics and sources of VOCs were explored. The daily average concentration of PM2.5 and total VOCs (TVOCs) ranged from 54 to 239 µg/m3andfrom 15.6 to 57.1 ppbv with an average value of 112 ± 45 µg/m3 and 36.1 ± 21.0 ppbv, respectively during the entire period. The values of PM2.5 and TVOCs in Case 3 (pollution episode after the abolishment of "Nucleic Acid Screening Measures for all staff" policy) were 1.3 and 1.8 times of the values in the Case 1 (pollution episode during "Nucleic Acid Screening Measures for all staff" policy). The concentration of TVOCs in Case 1 and Case 3 were 48.4 ± 20.4 and 67.6 ± 19.6 ppbv, respectively, increased by 63 % and 188 % compared with values during clean days. Alkanes were found to be the most abundant compounds during the entire period. Equivalent volume contribution of halogenated hydrocarbon and oxygenated VOCs (15 %) were found the most in Case 3, followed by alkenes (10 %). Though the volume contributions of aromatics were the lowest (6 % in Case 1 and 7 % in Case 3), the highest increasing ratio was found from clean days to polluted episodes. Positive Matrix Factor model results showed that the main source of VOCs during the observation period was industrial emissions, which accounted for 30 % of the TVOCs, followed by vehicular emission (24 %) and combustion (23 %). The vehicular emission became the largest source during Case 1 (40 %) and Case 3 (29 %), consisting of large numbers of people going out after the blockade. Secondary organic aerosol formation potential (SOAFP) values were 37 and 109 µg/m3, respectively with the highest SOAFP contribution (17–19 μg/m3and 31–51 %) from vehicular emission both in Case 1 and Case 3. Solvent usage sources had the second highest SOAFP value (9 and 16 μg/m3) with the contributions of 23 and 31 % in Case 1 and Case 3 respectively. The control of vehicular emission, and solvent usage should be focused in Zhengzhou, and combustion was also important for the control of PM2.5 pollution in winter. [ABSTRACT FROM AUTHOR]

At this stage, there are many dust-hazardous industries, and occupational pneumoconiosis has a high incidence for a long time. To solve the dust pollution problem in coal processing plant workshops, the dust particle field and liquid droplet particle field were numerically simulated using computational fluid dynamics (CFD), and the influences of the induced airflow and corridor wind speed on the internal airflow field of the workshop were investigated to derive the dust pollution mechanism in the coal plant workshop under the change in the wind flow field. In this study, it was shown that the wind flow rate in the coal processing plant workshop is mainly affected by the corridor wind speed, and the higher the corridor wind speed is, the higher the wind flow rate. The induced airflow mainly affected the direction of the wind flow field in the workshop. According to the conclusions obtained from the simulations, a spray dust reduction system was designed for the coal processing plant workshop and applied in the Huangyuchuan coal processing plant. On-site measurement revealed that the dust reduction effect inside the coal processing plant workshop is obvious, and the overall dust reduction efficiency in the workshop reaches more than 94%, which meets the requirements of environmentally sustainable development and clean production. [ABSTRACT FROM AUTHOR]