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Understanding the spatiotemporal characteristics of PM 2.5 concentrations and identifying their associated meteorological factors can provide useful insight for implementing air pollution interventions. In this study, we used daily air quality monitoring data for 28 air pollution transmission channel cities in the Beijing-Tianjin-Hebei region during 2014-2019 to quantify the relative contributions of meteorological factors on spatiotemporal variation in PM 2.5 concentration by combining time series and spatial perspectives. The results show that annual mean PM 2.5 concentration significantly decreased in 24 of the channel cities from 2014 to 2019, but they all still exceeded the Grade II Chinese Ambient Air Quality Standards (35 μg m -3 ) in 2019. PM 2.5 concentrations exhibited clear spatial agglomeration in the most polluted season, and their spatial pattern changed slightly over time. Meteorological variables accounted for 31.96% of the temporal variation in PM 2.5 concentration among the 28 cities during the study period, with minimum temperature and average relative humidity as the most critical factors. Spatially, atmospheric pressure and maximum temperature played a key role in the distribution of PM 2.5 concentration in spring and summer, whereas the effect of sunshine hours increased greatly in autumn and winter. These findings highlight the importance of future clean air policy making, but also provide a theoretical support for precise forecasting and prevention of PM 2.5 pollution.

Urban emissions are a major contributor to atmospheric Hg budgets. Continuous measurements of total gaseous mercury (TGM) and particulate-bound mercury (PHg) in PM 2.5 were conducted from October 2015 to July 2016 in a metropolis, Jinan, in eastern China. Average TGM and PHg concentrations were 4.91 ± 3.66 ng m -3 and 451.9 ± 433.4 pg m -3 , respectively, in the entire study period. During the winter heating period (HP), mean concentrations of TGM and PHg were 5.79 ng m -3 and 598.7 pg m -3 , respectively, twice higher than those during the non-heating periods (NHPs). During the HP, TGM exhibited a distinct diurnal pattern with a peak in the morning and a minimum in the afternoon on less polluted days but a singular peak at midday on heavily polluted days. The diurnal variation of TGM during the NHPs was predominantly influenced by the variation in boundary layer height while during the HP by anthropogenic emissions. The ratio of PHg/PM 2.5 in Jinan was one to two orders of magnitude larger than those elsewhere worldwide and those in soil and coal, which suggested the high enrichment of PHg in PM 2.5 in Jinan. Correlation and principle component analysis results suggested that PHg and TGM had common combustion sources during the HP, whereas PHg resulted mainly from biomass burning and meteorological variations during the NHPs. High Hg concentrations in Jinan were mostly caused by emissions from coal-fired power plants, especially for those situated east of the sampling site. In addition, TGM and PHg concentrations significantly increased during haze and fog episodes, but decreased during a dust episode due possibly to strong ventilation conditions combined with partitioning of Hg between adsorption to PM 2.5 and coarse dust particles., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: We aimed to examine the associations of cognitive and structural social capital with subjective well-being (SWB) and mental health among internal migrants in five cities in China., Methods: We conducted healthy cities surveys from June 2017 to April 2018. In total, 3038 migrants submitted surveys. Generalized linear regressions for SWB and logistic regressions for mental health were used to examine the associations of social capital, SWB and mental health after controlling for covariates., Results: The median level of SWB was 75.7 (interquartile range 62.9-85.7). Self-rated health and physical activity were positively associated with SWB. The SWB level among migrants who perceived high individual social cohesion was much higher than that of their counterparts (unstandardized coefficients, β=7.01 [95% confidence interval {CI} 5.82 to 8.21]). The prevalence of poor mental health was 10.0%. High social cohesion (odds ratio [OR] 0.32 [95% CI 0.24 to 0.44]) and high social participation (OR 0.77 [95% CI 0.57 to 0.97]) were significantly associated with a low ratio of poor mental health when compared with their counterparts., Conclusions: Cognitive social capital is positively associated with SWB, while both cognitive and structural social capitals were negatively associated with poor mental health. It is beneficial to migrants' mental health and SWB to promote social participation and social cohesion., (© The Author(s) 2019. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Concentrations of PM 2.5 -bound trace elements have increased in China, with increasing anthropogenic emissions. In this study, long-term measurements of PM 2.5 -bound trace elements were conducted from January 2014 to January 2015 in the urban city of Jinan, east China. A positive matrix factorization model (PMF) and health risk assessment were used to evaluate the sources and health risks of these elements, respectively. Compared with most Chinese megacities, there were higher levels of arsenic, manganese, lead, chromium, and zinc in this city. Coal combustion, the smelting industry, vehicle emission, and soil dust were identified as the primary sources of all the measured elements. Heating activities during the heating period led to a factor of 1.3⁻2.8 higher concentrations for PM 2.5 and all measured elements than those during the non-heating period. Cumulative non-carcinogenic and carcinogenic risks of the toxic elements exceeded the safety levels by 8⁻15 and 10⁻18 times, respectively. Arsenic was the critical element having the greatest health risk. Coal combustion caused the highest risk among the four sources. This work provides scientific data for making targeted policies to control air pollutants and protect human health., Competing Interests: The authors declare no conflict of interest.

Objectives: To examine the association of FVI and frailty in Chinese elders., Design: A sectional study was conducted in three cities (Shanghai, Zhengzhou, and Baoji) in China from June 2017 to June 2018., Participants: A total of 5699 participants from 49 districts were included in the current study by two-stage sampling methods., Measurements: Frailty was measured by a validated Chinese version of the FRAIL scale. FVI per day was measured by two single questions., Results: The sample proportion with sufficient fruit intake was 36.7%, and 44.7% reported sufficient vegetable intake. The sample proportions that were robust, pre-frail, and frail were 43.6%, 38.3%, and 18.1%, respectively. Compared with low FVI, after including covariates, the odds ratio (OR) of frailty was 0.84 (95% CI: 0.73-0.97) for moderate fruit intake and 0.81 (95% CI: 0.70-0.94) for enough fruit intake; the OR of frailty was 0.83 (95% CI: 0.68-0.91) for moderate vegetable intake and 0.77 (95% CI: 0.64-0.93) for enough vegetable intake., Conclusion: High FVI was negatively associated with the OR of frailty in Chinese elders. This finding implies it is important to promote FVI among adults to prevent frailty., Competing Interests: No potential conflict of interest was reported by the authors.