Identification of NOx emissions and source characteristics by TROPOMI observations - A case study in north-central Henan, China.

With the development of industries, air pollution in north-central Henan is becoming increasingly severe. The TROPOspheric Monitoring Instrument (TROPOMI) provides nitrogen dioxide (NO2) column densities with high spatial resolution. Based on TROPOMI, in this study, the nitrogen oxides (NOx) emissions in north-central Henan are derived and the emission hotspots are identified with the flux divergence method (FDM) from May to September 2021. The results indicate that Zhengzhou has the highest NOx emissions in north-central Henan. The most prominent hotspots are in Guancheng Huizu District (Zhengzhou) and Yindu District (Anyang), with emissions of 448.4 g/s and 300.3 g/s, respectively. The Gaussian Mixture Model (GMM) is applied to quantify the characteristics of emission hotspots, including the diameter, eccentricity, and tilt angle, among which the tilt angle provides a novel metric for identifying the spatial distribution of pollution sources. Furthermore, the results are compared with the CAMS global anthropogenic emissions (CAMS-GLOB-ANT) and Multi-resolution Emission Inventory model for Climate and air pollution research (MEIC), and they are generally in good agreement. However, some point sources, such as power plants, may be missed by both inventories. It is also found that for emission hotspots near transportation hubs, CAMS-GLOB-ANT may not have fully considered the actual traffic flow, leading to an underestimation of transportation emissions. These findings provide key information for the accurate implementation of pollution prevention and control measures, as well as references for future optimization of emission inventories. Consequently, deriving NOx emissions from space, quantifying the characteristics of emission hotspots, and combining them with bottom-up inventories can provide valuable insights for targeted emission control.

Research on the diurnal variation characteristics of ozone formation sensitivity and the impact of ozone pollution control measures in "2 + 26" cities of Henan Province in summer.

Near-surface ozone pollution is becoming an increasingly serious air quality issue in China, especially in "2 + 26" cities (Beijing-Tianjin-Hebei and nearby cities). HN2 + 26 cities ("2 + 26" cities of Henan Province) are located in the south of "2 + 26" cities, with frequent and severe ozone pollution events in recent years. This study investigated the diurnal evolution characteristics of ozone formation sensitivity (OFS) of HN2 + 26 cities from May to September in 2021 by the innovative combination of Global Ozone Monitoring Experiment (GOME-2B) and Ozone Monitoring Instrument (OMI) satellite data, and assessed the impact of ozone pollution control measures (OPCMs) implemented from June 26 to July 1, 2021. The localized FNR (ratio of formaldehyde to nitrogen dioxide of satellite measurement) threshold (1.4-2.55) was established, and it was found that OFS in May-September 2021 was mainly in VOCs-limited regime in the morning (∼10:00), while transitional/NOx-limited regime in the afternoon (∼14:00). Three periods (before, during and after the OPCMs) were divided to evaluate the impact of OPCMs on OFS. It was indicated that OPCMs had no impact on the morning OFS, but had a significant impact on the afternoon OFS. Specifically, the OFS in two industrial cities Xinxiang (XX) and Zhengzhou (ZZ) shifted from transitional regime to NOx-limited regime after the OPCMs. We further investigated OFS differences between urban and suburban areas and found that OFS shift of XX only existed in urban areas, while that of ZZ existed in both urban and suburban areas. We compared their measures and found that it is effective to take hierarchical control measures on different levels of ozone pollution days to alleviate ozone pollution. This study provides an improved understanding of diurnal evolution characteristics of OFS and the impacts of OPCMs on it, which will provide a theoretical basis for formulating more scientific ozone pollution control policies.

Regional variation of medical expenditures attributable to hypertension in China's middle-aged and elderly population.

BACKGROUND: Hypertension is a prevalent and costly health condition in China. Little is known about variation of the inpatient and outpatient expenditures attributable to hypertension between prefecture-level administrative regions (PARs) and the drivers of such variation among China's middle-aged and elderly population. METHODS: We obtain data from China Health and Retirement Longitudinal Survey between 2011 and 2015, panel tobit models were used in our study to estimate differences across 122 PARs. Expenditure variation was explained by the characteristics of individuals and regions, including measures of healthcare supply. RESULTS: The cost of treatment for patients with hypertension varies greatly geographically, with the highest outpatient and inpatient costs being 77 and 102 times the lowest, respectively. After adjustment for the individual and PAR character, there are associations between expenditure and region bed density. CONCLUSION: There were significant regional differences in the outpatient and inpatient costs of middle-aged and elderly patients with hypertension in China, the difference between individuals may be an important reason, which has little to do with regional economic development differences, but is related to regional bed density.

Correlation between serum levels of C-reactive protein and infant pneumonia: A meta-analysis.

Experimental data imply that serum C-reactive protein (CRP) is a marker of general systemic inflammation, and inflammation may have a role in the development of pneumonia. The aim of the present study was to investigate the associations of serum CRP levels in infant patients with pneumonia by meta-analysis. The Science Citation Index, Cochrane Library, PubMed, Embase, CINAHL, Current Contents and two Chinese (CMB and CNKI) databases were searched. Studies were pooled and standard mean difference (SMD) and the corresponding 95% confidence interval (CI) were calculated. Subgroup analyses and publication bias detection were also conducted. The statistical analysis was conducted using Stata software version 12.0. Serum CRP levels were analyzed in 10 clinical case-control studies (652 infants with pneumonia and 845 healthy controls); significant differences in serum CRP levels were observed between infants with pneumonia and the healthy controls (SMD=4.41, 95% CI: 3.34-5.47, P<0.001). Ethnicity-stratified subgroup analysis detected that high levels of serum CRP may be the main risk factor for infant pneumonia in Asian, African and Caucasian populations (all P<0.05). Serum CRP levels were statistically higher in infants with pneumonia than in healthy infants, and thus serum levels of CRP may have independent diagnostic value for pneumonia in children.