Response of PM2.5 pollution to meteorological and anthropogenic emissions changes during COVID-19 lockdown in Hunan Province based on WRF-Chem model.

In December 2019, the New Crown Pneumonia (the COVID-19) outbroke around the globe, and China imposed a nationwide lockdown starting as early as January 23, 2020. This decision has significantly impacted China's air quality, especially the sharp decrease in PM2.5 (aerodynamic equivalent diameter of particulate matter less than or equal to 2.5 µm) pollution. Hunan Province is located in the central and eastern part of China, with a "horseshoe basin" topography. The reduction rate of PM2.5 concentrations in Hunan province during the COVID-19 (24.8%) was significantly higher than the national average (20.3%). Through the analysis of the changing character and pollution sources of haze pollution events in Hunan Province, more scientific countermeasures can be provided for the government. We use the Weather Research and Forecasting with Chemistry (WRF-Chem, V4.0) model to predict and simulate the PM2.5 concentrations under seven scenarios before the lockdown (2020.1.1-2020.1.22) and during the lockdown (2020.1.23-2020.2.14). Then, the PM2.5 concentrations under different conditions is compared to differentiate the contribution of meteorological conditions and local human activities to PM2.5 pollution. The results indicate the most important cause of PM2.5 pollution reduction is anthropogenic emissions from the residential sector, followed by the industrial sector, while the influence of meteorological factors contribute only 0.5% to PM2.5. The explanation is that emission reductions from the residential sector contribute the most to the reduction of seven primary contaminants. Finally, we trace the source and transport path of the air mass in Hunan Province through the Concentration Weight Trajectory Analysis (CWT). We found that the external input of PM2.5 in Hunan Province is mainly from the air mass transported from the northeast, accounting for 28.6%-30.0%. To improve future air quality, there is an urgent need to burn clean energy, improve the industrial structure, rationalize energy use, and strengthen cross-regional air pollution synergy control.

Causes of the unexpected slowness in reducing winter PM2.5 for 2014-2018 in Henan Province.

Toughest-ever clean air actions in China have been implemented nationwide to improve air quality. However, it was unexpected that from 2014 to 2018, the observed wintertime PM2.5 (particulate matter with an aerodynamic diameter of less than 2.5 µm) concentrations showed an insignificant decrease in Henan Province (HNP), a region in the west of the North China Plain. Emission controls seem to have failed to improve winter air quality in HNP, which has caused great confusion in formulating the next air improvement strategy. We employed a deweathering technique to decouple the impact of meteorological conditions. The results showed that the deweathered PM2.5 trend was -3.3%/yr in winter from 2014 to 2018, which had a larger decrease than the observed concentrations (-0.9%/yr), demonstrating that emission reduction was effective at improving air quality. However, compared with the other two megacity clusters, Beijing-Tianjin-Hebei (BTH) (-8.4%/yr) and Yangtze River Delta (YRD) (-7.4%/yr), the deweathered decreasing trend of PM2.5 for HNP remained slow. The underlying mechanism driving the changes in PM2.5 and its chemical components was further explored, using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). Model simulations indicated that nitrate dominated the increase of PM2.5 components in HNP and the proportions of nitrate to total PM2.5 increased from 22.4% in January 2015 to 39.7% in January 2019. There are two primary reasons for this phenomenon. One is the limited control of nitrogen oxide emissions, which facilitates the conversion of nitric acid to particulate nitrate by ammonia. The other is unfavourable meteorological conditions, particularly increasing humidity, further enhancing nitrate formation through multiphase reactions. This study highly emphasizes the importance of reducing nitrogen oxide emissions owing to their impact on the formation of particulate nitrate in China, especially in the HNP region.

Management of SARS-CoV-2 Omicron Variant Community Screenings in Shanghai, China: A Cross-Sectional Study.

Background: Community screening for SARS-CoV-2 Omicron variant plays a significant role in controlling the spread of infection. However, loopholes may exist in the current management of community screening in Shanghai, China. The objective of this study was to discover loopholes in the management of community screening for SARS-CoV-2 Omicron variant in Shanghai, China and provide targeted solutions. Methods: The cross-sectional study was carried out April 4 to April 30, 2021, among residential committee directors from the Putuo District, Pudong District, and Minhang District of Shanghai, China. Data were collected using a self-designed questionnaire about the management of nucleic acid testing (NAT) sampling in communities through the network platform powered by www.wjx.cn. Results: A total of 203 residential committee directors responded to the survey. Of them, 47.3% were not accepted training and 40.4% were not aware of cross-infection. Comparison among sampling sites and communities, high-risk group contained lower proportion of community training (P = 0.093~0.200), higher awareness of cross-infection (P = 0.039~0.777), more medical workers (P = 0.007~0.724) and more tests performed (P = 0.001~0.992). Larger communities had more medical workers, sampling sites, sampling tables (P = 0.000) and higher awareness of cross-infection (P = 0.009), but lower proportion of community training (P = 0.051). Conclusion: Overall, community training and awareness of infection control were inadequate. Government or institutions should organize the community training and raise the awareness of infection control. Significant differences exist in NAT management patterns between sampling sites, as well as communities of different sizes. Residential community directors minimize high-risk sampling point settings in the future. Special personnel designated by the government or institutions should tour to guide each sampling site.

Chest CT imaging features and clinical outcome of coronavirus disease 2019 (COVID-19): A single-center case study in Ningbo, China.

OBJECTIVE: The purpose of this study was to investigate the chest CT imaging features and clinical outcome of coronavirus disease 2019 (COVID-19) in Ningbo, China. METHODS: In this retrospective study, twenty-eight confirmed and seven highly suspected cases of COVID-19 were enrolled in Ningbo first hospital from January 26, 2020 to March 5, 2020. Cases were confirmed by real-time polymerase chain reaction (RT-PCR). The initial and follow-up chest CT imaging features, epidemiological history, and outcome were analyzed. RESULTS: The average age of the patients was 57.3 ± 15.3 years (range: 27-96 years), including 25 females and 10 males. On CT images, 89.3% (25/28) confirmed and 100% (7/7) suspected patients had ground-glass opacities (GGOs), and GGOs with mixed consolidations were observed in 35.7% (10/28) confirmed and 42.9% (3/7) suspected cases, most of these lesions were distributed under the peripheral of both lungs. 17 confirmed and 4 suspected cases had a history of participating in Ningbo Tian-tong Temple rituals and all had GGOs in their lungs during the initial CT scan. As of March 25, 2020, the lung lesions of our cases were significantly resolved and all patients have been discharged from the hospital. CONCLUSION: The most common chest CT features are multiple bilateral and peripheral GGOs with mixed consolidations or not in the lungs of patients with COVID-19. Chest CT plays an important role in the diagnosis and monitoring treatment response of this disease. There was no reported death in our cases.