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Sulfate aerosols exert profound impacts on human and ecosystem health, weather, and climate, but their formation mechanism remains uncertain. Atmospheric models consistently underpredict sulfate levels under diverse environmental conditions. From atmospheric measurements in two Chinese megacities and complementary laboratory experiments, we show that the aqueous oxidation of SO2 by NO2 is key to efficient sulfate formation but is only feasible under two atmospheric conditions: on fine aerosols with high relative humidity and NH3 neutralization or under cloud conditions. Under polluted environments, this SO2 oxidation process leads to large sulfate production rates and promotes formation of nitrate and organic matter on aqueous particles, exacerbating severe haze development. Effective haze mitigation is achievable by intervening in the sulfate formation process with enforced NH3 and NO2 control measures. In addition to explaining the polluted episodes currently occurring in China and during the 1952 London Fog, this sulfate production mechanism is widespread, and our results suggest a way to tackle this growing problem in China and much of the developing world. [ABSTRACT FROM AUTHOR]

Tropospheric ozone (O3) is a trace gas playing important roles in atmospheric chemistry, air quality and climate change. In contrast to North America and Europe, long-term measurements of surface O3 are very limited in China. We compile available O3 observations at Mt. Tai - the highest mountain over the North China Plain - during 2003-2015 and analyze the decadal change of O3 and its sources. A linear regression analysis shows that summertime O3 measured at Mt. Tai has increased significantly by 1.7 ppbv yr-1 for June and 2.1 ppbv yr-1 for the July-August average. The observed increase is supported by a global chemistry-climate model hindcast (GFDL-AM3) with O3 precursor emissions varying from year to year over 1980-2014. Analysis of satellite data indicates that the O3 increase was mainly due to the increased emissions of O3 precursors, in particular volatile organic compounds (VOCs). An important finding is that the emissions of nitrogen oxides (NOx) have diminished since 2011, but the increase of VOCs appears to have enhanced the ozone production efficiency and contributed to the observed O3 increase in central eastern China. We present evidence that controlling NOx alone, in the absence of VOC controls, is not sufficient to reduce regional O3 levels in North China in a short period. [ABSTRACT FROM AUTHOR]

erosol size distributions, trace gas, and PM concentrations have been measured in urban Jinan, China, over 6 months in 2007 and 2008, covering spring, summer, fall, and winter time periods. Number concentrations of particles (10-2,500 nm) were 16,200, 13,900, 11,200, and 21,600 cm in spring, summer, fall, and winter, respectively. Compared with other urban studies, Jinan has higher number concentrations of accumulation-mode particles (100-500 nm) and particles (10-2,500 nm), but lower concentrations of ultrafine particles (10-100 nm). The number, surface and volume concentrations, and size distributions of particles showed obvious seasonal variation and are also influenced by traffic emissions. Through correlation analysis, traffic emissions are proposed to be a more important contributor to Atkien-mode and accumulation-mode particles than coal firing. Around midday, the presence of nanoparticles and new particle formation is limited to pre-existing particles from traffic emissions and the mass transport of particles from suburban and rural areas. Compared with other studies in urban areas of Europe and the USA, the variation of particle number concentration and related gas concentration in Jinan between weekdays and weekends is smaller and the reasons has been deduced. [ABSTRACT FROM AUTHOR]

Background Cognitive frailty is a cognitive impairment state between normal aging and dementia. Cognitive frailty is associated with higher possibility of negative clinical events than simple frailty or cognitive impairment in older people. As cognitive frailty could be reversible toa certain degree, early identification of high-risk groups and timely intervention are particularly important in reducing adverse prognoses and improving the quality of life of elderly patients in their later years. Objective To investigate the prevalence and influencing factors of cognitive frailty, and its relationship with two-year post-discharge mortality in hospitalized elderly patients with comorbidities. Methods The data were collected from part of the project "Research and Demonstration of Clinical Management and Community-based Continuing Care Models for Older People with Comorbidities", involving a cluster sample of older inpatients with comorbidity aged≥60 years recruited from Department of Gerontology, Chengdu Fifth People's Hospital from November 2015 to January 2018. Demographics, chronic disease prevalence, and comprehensive geriatric assessment results were collected. Cognitive frailty was assessed by the FRAIL scale and Mini-Mental State Examination. Binary Logistic regression was used to analyze the influencing factors of cognitive frailty. The survival status was investigated at the end of a two-year follow-up after discharge. Cox regression was used to analyze the relationship of cognitive frailty with two-year post-discharge mortality. Results A total of 554 cases were included, and 15.9% (88/554) of them had cognitive frailty. Compared with non-cognitive frailty group, cognitive frailty group had older average age, lower prevalence of high school education or above, lower average family care score, higher prevalence of malnutrition, depression, dependence in activities of daily living and balance dysfunction (P

Haze episodes often hit urban cities in China recently. Here, we present several continuous haze episodes with extremely high PM2.5 levels that occurred over several weeks in early 2013 and extended across most parts of the northern and eastern China-far exceeding the Beijing-Tianjin-Hebei region. Particularly, the haze episode covered ~1 million km² on January 14, 2013 and the daily averaged PM2.5 concentration exceeded 360 µg m-3 in Ji'nan. The observed maximum hourly PM2.5 concentration in urban Ji'nan reached 701 µg m-3 at 7:00 am (local time) in January 30. During these haze episodes, several fog events happened and the concurrent fog water was found to be seriously polluted. For the fog water collected in Ji'nan from 10:00 pm in January 14 to 11:00 am in January 15, sulfate, nitrate, and ammonium were the major ions with concentrations of 1.54 x 106, 8.98 x 105, and 1.75 x 106 µeq L- 1, respectively, leading to a low in-situ pH of 3.30. The sulfate content in the fog sample was more than 544 times as high as those observed in other areas. With examination of the simultaneously observed data on PM2.5 and its chemical composition, the fog played a role in scavenging and removing fine particles from the atmosphere during haze episodes and thus was seriously contaminated. However, the effect was not sufficient to obviously cleanse air pollution and block haze episodes. [ABSTRACT FROM AUTHOR]