Rabies vaccination adherence and associated factors among rabies-exposed patients in Shenzhen, China: a hospital-based cross-sectional study.

Adherence to post-exposure prophylaxis and post-exposure vaccination (PEV) is an important measure to prevent rabies. The purpose of this study was to explore the adherence to the vaccination protocol and its influencing factors among rabies-exposed patients in Shenzhen, China. A cross-sectional survey was conducted in a tertiary hospital in Shenzhen, China, to obtain epidemiological characteristics of patients; knowledge, attitude, and practice scores of rabies prevention; and medical records. A total of 326 patients requiring full rabies PEV were included in this study, and only 62% (202) completed the full course of vaccination according to the norms of the vaccination guidelines. After multifactor logistic regression, the factors influencing adherence to vaccination were as follows: age 31 to 40 years, time spent to reach the nearest rabies prevention clinic was >60 min, the time of injury was at night to early morning, the place of injury was a school/laboratory, the animal causing injury was a cat, the health status of the animal causing injury could not be determined, and patients with higher practice scores (all p<0.05). Understanding the factors influencing rabies vaccination adherence among rabies-exposed patients in urban areas of China and promote changes in patients' practice toward rabies prevention is essential for rabies elimination by 2030.

The impact of integrated care on health care utilization and costs in a socially deprived urban area in Germany: A difference-in-differences approach within an event-study framework.

We investigated the impact of an integrated care initiative in a socially deprived urban area in Germany. Using administrative data, we empirically assessed the causal effect of its two sub-interventions, which differed by the extent to which their instruments targeted the supply and demand side of healthcare provision. We addressed confounding using propensity score matching via the Super Learner machine learning algorithm. For our baseline model, we used a two-way fixed-effects difference-in-differences approach to identify causal effects. We then employed difference-in-differences analyses within an event-study framework to explore the heterogeneity of treatment effects over time, allowing us to disentangle the effects of the sub-interventions and improve causal interpretation and generalizability. The initiative led to a significant increase in hospital and emergency admissions and non-hospital outpatient visits, as well as inpatient, non-hospital outpatient, and total costs. Increased utilization may indicate that the intervention improved access to care or identified unmet need.

Treatments and prognostic factors for bone and soft tissue sarcoma in non-urban areas in Japan.

BACKGROUND: Although bone and soft tissue sarcoma is recognized as a rare cancer that originates throughout the body, few comprehensive reports regarding it have been published in Japan. PATIENTS AND METHODS: Bone and soft tissue sarcomas were tabulated from the Cancer Registries at eight university hospitals in the Chugoku-Shikoku region. Prognostic factors in cases were extracted in a single facility and have been analyzed. RESULTS: From 2016 to 2019, 3.4 patients with bone and soft tissue sarcomas per a general population of 100,000 were treated at eight university hospitals. The number of patients who underwent multidisciplinary treatment involving collaboration among multiple clinical departments has been increasing recently. In the analysis carried out at a single institute (Ehime University Hospital), a total of 127 patients (male/female: 54/73) with an average age of 67.0 y (median 69.5) were treated for four years, with a 5-year survival rate of 55.0%. In the analysis of prognostic factors by multivariate, disease stage and its relative treatment, renal function (creatinine), and a patient's ability of self-judgment, and a patient's mobility and physical capability were associated with patient prognosis regarding bone and soft tissue sarcomas. Interestingly, age did not affect the patient's prognosis (> 70 vs ≦ 70). CONCLUSIONS: Physical and social factors may affect the prognosis of patients with bone and soft tissue sarcomas, especially those living in non-urban areas.

Situational Analysis of Barriers to Continuity of End-of-Life Care in Urban Areas, Bangkok.

This qualitative study was designed to describe the continuity of end-of-life care and identify barriers to continuity in urban Bangkok. Continuity of care is considered an essential part of palliative care to promote the quality of life of patients at the end of life. The majority of studies have been conducted exploring continuity of care in rural communities. However, few studies have focused on urban areas, particularly in big cities. Twelve healthcare providers were the participants, including nurses in inpatient units, and in the Health Community and Continuity of Care Unit, a palliative care physician, and social workers. The data collection consisted of individual interviews, field notes, and observations. Content analysis was used to analyze data and identify barriers. The continuity of end-of-life care in a selected setting was fragmented. Three main barriers to the continuity of end-of-life care consisted of misunderstandings about patients who required palliative care, staff workloads, and incomplete patient information. The development of a comprehensive patient information sheet for communication among a multidisciplinary team could promote continuity of end-of-life care from hospital to home. An interprofessional training course on continuity of end-of-life care is also recommended. Finally, the staff workload should be monitored and managed.

Evaluation of a Ground Subsidence Zone in an Urban Area Using Geophysical Methods.

An important geological risk to which many towns in Puglia are exposed is sinking cavities in urban areas. For urban centers, studying, mapping, providing geological and speleological descriptions, classifying, and cataloging the forms and types of cavities is essential because cavities are linked to past local anthropic and natural processes at different sites. These circumstances could lead to the enhancement of existing underground cavities in urban areas through conservation and continuous monitoring. Unfortunately, in many cases, these underground cavities have been used as landfills and subsequently abandoned. In late March 2007, one of these cavities collapsed inside Gallipoli's inhabited center, causing damage to the structures but fortunately not human lives. In the area surrounding the collapsed cavity, a series of geophysical investigations were undertaken using ground penetrating radar in an attempt to delimit the area of collapse and develop possible interventions for restoration. In the same area, these measures were repeated 16 years later in December 2022 due to another collapse. The comparison between data acquired in these two periods shows that there were no strong changes apart from an increased presence of subsoil moisture in 2022.

Characteristics of Gaseous Elemental Mercury in a Suburban Area of Shanghai, China.

To clarify gaseous elemental mercury (GEM) in suburban megacities in the Yangtze River Delta region, China, we observed GEM concentrations from December 2019 to November 2020 in Wujing town, a suburban area of Shanghai. The annual mean GEM concentration was 1.44 ± 0.88 ng m-3. Compared with the historical monitoring data of GEM in Shanghai over the past 10 years, the concentration of GEM showed a decreasing trend. The monthly mean concentrations of GEM showed clear seasonal variation, with higher values in the spring and winter. In spring and winter, typical Hg pollution events were observed, which could be mostly associated with increased local anthropogenic activity and temperature inversion. The results of the correlation analysis of the daily mean GEM concentrations with the AQI and backward trajectory calculations indicate that mercury pollution at monitoring sites can be affected by local, regional and interregional influences.

Ability to pay and catastrophic health expenditure of urban and rural deceased households over the past decade (2009-2018).

INTRODUCTION: Examining the equity of health care and financial burden in households of deceased individuals in urban and rural areas is crucial for understanding the risks to both national and individual household finances. However, there is a lack of research on catastrophic health expenditure (CHE) in these households, specifically in urban and rural contexts. This study aims to identify the ability to pay and equity of CHE for both households of deceased individuals in urban and in rural areas. METHODS: This study analysed data from the Korea Health Panel for 10 years (2009-2018) and targeted 869 deceased individuals and their households in the Republic of Korea (South Korea). Annual household income and living costs were adjusted based on equivalent household size, and the difference between these values represented the household's ability to pay. Out-of-pocket (OOP) expenditure included copayments and uninsured healthcare expenses for emergency room visits, inpatient care, outpatient treatments and prescription medications. CHE was defined as OOP expenditure reaching or exceeding 40% of the household's ability to pay. ANCOVA was performed to control for confounding variables, and the equity of CHE prevalence between urban and rural area was assessed using χ2 analysis. RESULTS: Compared to urban households, the rural households of deceased individuals had, respectively, fewer members (2.7 v 2.4, p=0.03), a higher rate of presence of a spouse (63.8% v 70.7%, p=0.04) and a higher economic activity rate (12.7% v 20.5%, p=0.002). The mean number of comordities before death was 3.7 in both urban and rural areas, and there was no difference in the experience of using over-the-counter medicines for more than 3 months, emergency room, hospitalisation, and outpatient treatment. In addition, annual household OOP expenditures in urban and rural areas were US$3020.20 and US$2812.20, respectively, showing no statistical difference (p=0.341). This can be evaluated as a positive effect of various policies and practices aimed at alleviating urban-rural health equity. However, the financial characteristics of the household of the deceased in the year of death differed decisively between urban and rural areas. Compared to urban households, the annual income of rural households (US$15,673.80 v US$12,794.80, respectively, p≤0.002) and the annual ability to pay of rural households (US$14,734.10 v US$12,069.30, respectively, p=0.03) were lower. As a result, the prevalence of CHE was higher in rural areas than in urban areas (68.3% v 77.6%, p=0.003). CONCLUSION: The findings of this study highlight the higher risk of CHE in rural areas due to the lower income level and ability to pay of the household of the deceased. It is evident that addressing the issue of CHE requires broader social development and policy efforts rather than individual-level interventions focused solely on improving health access and controlling healthcare costs. The findings of this study contribute to the growing evidence that income plays a crucial role in rural health outcomes.

Yeasts associated with mines on tree leaves in the urban areas.

Mines on tree leaves and undamaged leaves were studied to investigate yeast complexes in urban areas (Aesculus hippocastanum, miner - Cameraria ohridella; Betula verrucosa, miner - Caloptilia betulicola; Populus nigra, miner - Lithocolletis populifoliella; Quercus robur, miner - Tischeria companella; Salix caprea, miner - Trachys minuta; Syringa vulgaris, miner - Caloptilia syringella; Tilia cordata, miner - Phyllonorycter issikii; Ulmus laevis, miner - Carpatolechia fugitivella). The abundance and taxonomic structure of yeasts were studied using a surface plating method on solid media (GPY agar). Identification of yeast species was based on the ITS rDNA nucleotide sequence. The average abundance of yeasts during the first stages of mine formation in the internal tissues of leaves was 103 cfu/g. After 23-25 days, during the last stage of larval metamorphosis before mine destruction, the abundance of yeasts in the mines increased by two orders of magnitude to 105 cfu/g. No significant differences were observed in the abundance of yeasts in mines formed by different insects on different trees. A total of twelve yeast species were observed. The fast-growing ascomycetous yeasts Hanseniaspora uvarum and H. occidentalis dominated the mines. On undamaged leaves, the basidiomycetous yeasts Papiliotrema flavescens and Rhodotorula mucilaginosa, typical in the phyllosphere, dominated. The opportunistic yeast Candida parapsilosis was detected in the yeast complexes of all mines examined and was not found on the surface of leaves. Comparison of the relative abundance of yeast species between the studied mines and undamaged leaves using principal component analysis showed that all studied yeast communities in the mines were significantly different from the epiphytic yeast complexes of the undamaged leaves. Thus, miners in urban environments provoke the formation of short-lived endophytic yeast complexes with high abundance of Hanseniaspora. For leaf miners, the yeasts serve primarily as a food source for insect larvae rich in vitamins and amino acids. The adult leaf miners, in turn, contribute to the reproduction of the yeasts and create favorable conditions for their development.

Urban green space and mental health among people living alone: The mediating roles of relational and collective restoration in an 18-country sample.

Rates of living alone, especially in more urbanised areas, are increasing across many industrialised countries, with associated increases in feelings of loneliness and poorer mental health. Recent studies have suggested that access to nature (e.g. parks and green spaces) can reduce the stressors associated with loneliness, partly through providing opportunities to nurture personal relationships (relational restoration) and engage in normative community activities (collective restoration). Such associations might vary across different household compositions and socio-demographic or geographical characteristics, but these have not been thoroughly tested. Using data collected across 18 countries/territories in 2017-2018, we grouped urban respondents into those living alone (n = 2062) and those living with a partner (n = 6218). Using multigroup path modelling, we tested whether the associations between neighbourhood greenspace coverage (1-km-buffer from home) and mental health are sequentially mediated by: (a) visits to greenspace; and subsequently (b) relationship and/or community satisfaction, as operationalisations of relational and collective restoration, respectively. We also tested whether any indirect associations varied among subgroups of respondents living alone. Analyses showed that visiting green space was associated with greater mental well-being and marginally lower odds of using anxiety/depression medication use indirectly, mediated via both relationship and community satisfaction. These indirect associations were equally strong among respondents living alone and those living with a partner. Neighbourhood green space was, additionally, associated with more visits among respondents living with a partner, whereas among those living alone, this was sensitive to the green space metric. Within subgroups of people living alone, few overall differences were found. Some indirect pathways were, nevertheless, stronger in males, under 60-year-olds, those with no financial strain, and residents in warmer climates. In conclusion, supporting those living alone, as well as those living with a partner, to more frequently access their local greenspaces could help improve mental health via promoting relational and collective restoration.

The effect of rural and urban life on peritonitis rates in chronic peritoneal patients.

BACKGROUND: It has been reported that living far from the peritoneal dialysis (PD) unit is a risk factor for peritonitis. Considering that PD units are urban located; the question of whether living in a rural area compared to an urban area is a risk factor for peritonitis has arisen. METHODS: From March 2010 to August 2020, 335 episodes of peritonitis in 202 PD patients followed in a single center were evaluated retrospectively. People living in areas with a population <1000 were defined as living in rural areas regardless of their distance from the PD center. Cox regression analysis was used to identify independent factors associated with peritonitis. RESULTS: A total of 202 PD patients were followed during 791 patient-years (mean follow-up of 3.9 years per patient). Total patients had 335 episodes of peritonitis and the rate of peritonitis was 0.42 episodes per year (episodes/patient-year). Cox regression analysis revealed that living environment (urban vs. rural) was not a risk factor for peritonitis (p = 0.57). CONCLUSIONS: In Turkey, we report that living in a rural area in our region is not a risk factor for peritonitis. It is not the right approach for both the physician and the patient to be reluctant in the choice of PD due to the concern of peritonitis in rural areas.

The Environmental Impacts of Radio Frequency and Power Line Communication for Advanced Metering Infrastructures in Smart Grids.

In the neighborhood area network (NAN), the advanced metering infrastructure (AMI) enables a bidirectional connection between the smart meter (SM) and the data concentrator (DC). Sensors, such as smart meter nodes or environmental sensor nodes, play a crucial role in measuring and transmitting data to central units for advanced monitoring, management, and analysis of energy consumption. Wired and wireless communication technologies are used to implement the AMI-NAN. This paper delves into a novel approach for optimizing the choice of communication medium, air for radio frequency (RF) or power lines for power line communication (PLC), between the SM and DC in the context of the AMI-NAN. The authors methodically select the specific technologies, RF and NB-PLC (narrowband power line communication), and meticulously characterize their attributes. Then, a comparative analysis spanning rural, urban, and industrial settings is conducted to evaluate the proposed method. The overall reliability performance of the AMI-NAN system requires a packet error rate (PER) lower than 10%. To this end, an efficient approach is introduced to assess and enhance the reliability of NB-PLC and RF for AMI-NAN applications. Simulation results demonstrate that wireless communication is the optimal choice for the rural scenario, especially for a signal-to-noise ratio (SNR) lower than 25 dB. However, in urban environments characterized by higher SNR values and moderately dense networks, NB-PLC gains prominence. In denser networks, it outperforms wireless communication, exhibiting a remarkable 10 dB gain for a bit error rate (BER) of 10-3. Moreover, in industrial zones characterized by intricate network topologies and non-linear loads, the power line channel emerges as the optimal choice for data transmission.

Cultivated land multifunctionality in undeveloped peri-urban agriculture areas in China: Implications for sustainable land management.

The spatial planning and sustainable management of peri-urban cultivated land are key aspects of national development in many countries because of the continuing expansion of urban areas and deterioration of agro-ecosystem services. Detailed geo-informational investigation of cultivated land multifunctionality and the spatial interactions and dependencies of these multiple functions is required to inform the currently weak theoretical framework of multifunctionality at the peri-urban scale. Accordingly, the objective of this study was to construct a comprehensive methodology to identify and evaluate cultivated land multifunctionality in a spatial context. Geochemical data were used to measure cultivated land multifunctionality. We evaluated two main functions-the productive function and the ecological function-of an undeveloped peri-urban agriculture (PUA) area in the northern fringe of Changchun City in the black-soil region of northeastern China. For the ecological utilization of PUA areas, tradeoff and synergy analyses of cultivated land multifunctionality and coordinated development under complex land-use patterns were measured using a bivariate local Moran's I method. Results reveal considerable spatial heterogeneity in the two functions, with hotspots or coldspots being found in the PUA area. The productive function presents a less pronounced decreasing trend along the rural-to-urban gradient compared with the ecological function. Tradeoffs and synergies between the productive function and the ecological function occur mainly in the northern (more rural) part of the PUA area, where the spatial spillover effect of urbanization is relatively low. Cultivated land functions are strongly affected by urbanization-induced land-use types, and the coordinated areas of the productive function are generally consistent with those of the ecological function. According to these results, we delineate nine zones of multifunctionality in the studied PUA area. Given the importance of harmonizing cultivated land multifunctionality to manage limited land resources in a sustainable way, application of the GIS- and geochemistry-based multifunctionality evaluation scheme proposed in this study should be used to guide peri-urban spatial planning and land-use management and inform the policy arena concerning the transition of land use in urban peripheries.

Assessment of cyclic volatile methyl siloxanes (CVMSs) in indoor dust from different micro-environments in northern and central Vietnam.

Comprehensive studies on emerging contaminants like volatile methyl siloxanes in settled dust from different micro-environments are still limited. In this study, concentrations and distribution of cyclic volatile methyl siloxanes (CVMSs) including D3, D4, D5, and D6 were examined in indoor dust samples collected from various micro-environments in northern and central Vietnam. Concentrations of total CVMSs in the dust samples ranged from 86.0 to 5890 (median 755) ng/g and decreased in the order: waste processing workshops (median 1560; range 329-5890) > common houses (650; 115-1680) > university classrooms (480; 86.0-1540) > vehicle repair shops (295; 126-1950) ng/g. This observation suggests that informal waste processing activities are sources of CVMSs. Among the studied CVMSs, D5 was the most predominant compound (41 ± 14%), followed by D6 (26 ± 13%), D4 (23 ± 12%), and D3 (11 ± 11%). Moderate positive correlations between D3/D4, D4/D5, and D5/D6 were found. Median daily intake doses of D3, D4, D5, and D6 through dust ingestion were 0.016, 0.051, 0.11, and 0.054 ng/kg/d, respectively, which were comparable to water consumption and markedly lower than the air inhalation pathway.

The new WHO air quality guidelines for PM2.5: predicament for small/medium cities.

The global burden of disease estimated that approximately 7.1 million deaths worldwide were related to air pollution in 2016. However, only a limited number of small- and middle-sized cities have air quality monitoring networks. To date, air quality in terms of particulate matter is still mainly focused on mass concentration, with limited compositional monitoring even in mega cities, despite evidence indicating differential toxicity of particulate matter. As this evidence is far from conclusive, we conducted PM2.5 bioaccessibility studies of potentially harmful elements in a medium-sized city, Londrina, Brazil. The data was interpreted in terms of source apportionment, the health risk evaluation and the bioaccessibility of inorganic contents in an artificial lysosomal fluid. The daily average concentration of PM2.5 was below the WHO guideline, however, the chemical health assessment indicated a considerable health risk. The in vitro evaluation showed different potential mobility when compared to previous studies in large-sized cities, those with 1 million inhabitants or more (Curitiba and Manaus). The new WHO guideline for PM2.5 mass concentration puts additional pressure on cities where air pollution monitoring is limited and/or neglected, because decision making is mainly revenue-driven and not socioeconomic-driven. Given the further emerging evidence that PM chemical composition is as, or even more, important than mass concentration levels, the research reported in the paper could pave the way for the necessary inter- and intra-city collaborations that are needed to address this global health challenge.

A methodological proposal to analyze urban sprawl, negative environmental impacts, and land degradation in the case of João Pessoa City (Brazil) between 1991 and 2018.

Urbanization and changes in urban spaces have caused severe environmental and social problems in large Brazilian cities. As such, this study presents a methodological proposal to analyze urban sprawl, negative environmental impacts, and land degradation. The methodology employed involves a combination of remote sensing data, environmental modeling techniques, and mixed-method analyses of environmental impacts from 1991 to 2018. Analyzed variables included vegetation, surface temperature, water quality, and soil degradation within the study area. These variables were assessed based on an interaction matrix used to evaluate environmental impacts (low, medium, or high impacts). The obtained results show conflicts of land use and land cover (LULC), a lack of urban sanitation infrastructure, and an absence of environmental monitoring and inspection. A reduction of 24 km2 of arboreal vegetation was observed from 1991 to 2018. High values of fecal coliforms were found in March across nearly all analyzed points, indicating a seasonal discharge of effluents. The interaction matrix presented various negative environmental impacts, including increased land surface temperature, soil degradation, inappropriate solid waste disposal, devastation of remaining vegetation, water pollution by domestic effluents, and the incidence of erosive processes. Ultimately, the impact quantification determined that the study area has a medium degree of significance in terms of environmental impacts. Thus, refining this quantification method will contribute to future research by making the analysis processes more objective and efficient.

Impacts of pollution heterogeneity on population exposure in dense urban areas using ultra-fine resolution air quality data.

Traditional air quality data have a spatial resolution of 1 km or above, making it challenging to resolve detailed air pollution exposure in complex urban areas. Combining urban morphology, dynamic traffic emission, regional and local meteorology, physicochemical transformations in air quality models using big data fusion technology, an ultra-fine resolution modeling system was developed to provide air quality data down to street level. Based on one-year ultra-fine resolution data, this study investigated the effects of pollution heterogeneity on the individual and population exposure to particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), and ozone (O3) in Hong Kong, one of the most densely populated and urbanized cities. Sharp fine-scale variabilities in air pollution were revealed within individual city blocks. Using traditional 1 km average to represent individual exposure resulted in a positively skewed deviation of up to 200% for high-end exposure individuals. Citizens were disproportionally affected by air pollution, with annual pollutant concentrations varied by factors of 2 to 5 among 452 District Council Constituency Areas (DCCAs) in Hong Kong, indicating great environmental inequities among the population. Unfavorable city planning resulted in a positive spatial coincidence between pollution and population, which increased public exposure to air pollutants by as large as 46% among districts in Hong Kong. Our results highlight the importance of ultra-fine pollutant data in quantifying the heterogeneity in pollution exposure in the dense urban area and the critical role of smart urban planning in reducing exposure inequities.

Rural-Urban Differences in Diagnosed Cervical Artery Dissection in New York State.

BACKGROUND: Cervical artery dissection (CeAD) is a leading cause of stroke in young adults. Incidence estimates may be limited by under- or overdiagnosis. OBJECTIVE: We aimed to investigate if CeAD diagnosis would be higher in urban centers compared to rural regions of New York State (NYS). METHODS: For this ecological study, administrative codes were used to identify CeAD discharges in the NYS Statewide Planning and Research Cooperative System (SPARCS) from 2009 to 2014. Rural Urban Commuting Area (RUCA) codes were taken from the US Department of Agriculture and included the classifications metropolitan, micropolitan, small town, and rural. Negative binomial models were used to calculate effect estimates and 95% confidence limits (eß; 95% CL) for the association between RUCA classification and the number of dissections per ZIP code. Models were further adjusted by population. RESULTS: Population information was obtained from the US Census Bureau on 1,797 NYS ZIP codes (70.7% of NYS ZIP codes), 826 of which had at least 1 CeAD-related discharge from 2009 to 2014. Nonrural ZIP codes were more likely to report more CeAD cases relative to rural areas even after adjusting for population (metropolitan effect = eß 5.00; 95% CI: 3.75-6.66; micropolitan effect 3.02; 95% CI: 2.16-4.23; small town effect 2.34; 95% CI: 1.58-3.47). CONCLUSIONS: CeAD diagnosis correlates with population density as defined by rural-urban status. Our results could be due to underdiagnosis in rural areas or overdiagnosis with increasing urbanicity.

Concentration of selected elements in the hair of Madagascar girls in relation to nutritional status and place of residence.

Although the children malnutrition in Madagascar and the environmental pollution of this country has been widely discussed, there is no research on the differences in toxic elements accumulation in human body in dependence on nutritional status of Malagasy. Nine elements concentration (Al, As, Cd, Cr, Hg, Ni, Pb, Sn and Sb) was determined in scalp hair of 103 schoolgirls (8­15 years old), living in two areas: urban ­ close to Antananarivo (UR) and rural Berevo region (RU). Samples were analysed by an inductively coupled plasma optical emission spectrometer. The nutritional status was evaluated by Cole's index. Underweight was related to higher accumulation of Al, Cd and Cr in the hair girls, and more common among girls living in RU than UR region (42 % v. 28 %). Two-factor ANOVA showed differences in the Al and Cr content in the girls' hair depending both on their place of residence and nutritional status. This indicates additional consequence of malnutrition to the girls development and health.

Oxidation Flow Reactor Results in a Chinese Megacity Emphasize the Important Contribution of S/IVOCs to Ambient SOA Formation.

Oxygenated volatile organic compounds (OVOCs) and secondary organic aerosol (SOA) formation potential of ambient air in Guangzhou, China was investigated using a field-deployed oxidation flow reactor (OFR). The OFR was used to mimic hours to weeks of atmospheric exposure to hydroxyl (OH) radicals within the 2-3 min residence time. A comprehensive investigation on the variation of VOCs and OVOCs as a function of OH exposure is shown. Substantial formation of organic acids and nitrogen-containing OVOC species were observed. Maximum SOA formation in the OFR was observed following 1-4 equiv days' OH exposure. SOA produced from known/measured VOC/IVOC precursors such as single-ring aromatics and long-chain alkanes can account for 52-75% of measured SOA under low NOx and 26-60% under high NOx conditions based on laboratory SOA yield parametrizations. To our knowledge, this is the first time that the contribution (8-20%) of long-chain (C8-C20) alkane oxidation to OFR SOA formation was quantified from direct measurement. By additionally estimating contribution from unmeasured semivolatile and intermediate volatility compounds (S/IVOCs) that are committed with C8-C20 alkanes, 64-100% of the SOA formation observed in the OFR can be explained, signifying the important contribution of S/IVOCs such as large cyclic alkanes to ambient SOA.

Influence of meteorological parameters and oxidizing capacity on characteristics of airborne particulate amines in an urban area of the Pearl River Delta, China.

Nine amine species in atmospheric particles during haze and low-pollution days with low and high relative humidity (RH) were analyzed in urban Guangzhou, China. The mean concentrations of total measured amines (Æ©amines) in fine particles were 208 ± 127, 63.7 ± 21.3, and 120 ± 20.1 ng m-3 during haze, low pollution-low RH (LP-LRH), and low pollution-high RH (LP-HRH) episodes, respectively. The dominant amine species were methylamine (MA), dimethylamine (DMA), diethylamine (DEA) and dibutylamine (DBA), which in total accounted for 82-91% of the Æ©amines during different pollution episodes. The contributions of Æ©amines-C to water-soluble organic carbon (WSOC) and Æ©amines-N to water-soluble organic nitrogen (WSON) were 1.52% and 2.49% during haze, 1.24% and 1.96% during LP-LRH, and 2.00 and 2.98% during LP-HRH days, respectively. The mass proportion of Æ©amines in fine particles was higher during LP-HRH periods (0.19%) than during haze and LP-LRH periods (0.16%). The mass proportion of DBA in Æ©amines increased from 7% during haze and LP-LRH episodes to 25% during LP-HRH episodes. Compared with other amines, DBA showed a stronger linear relationship with RH (r = 0.867, p < 0.01), which demonstrates its high sensitivity to high RH conditions. Meteorological parameters (including RH, the mixed layer depth, wind speed and temperature), the oxidizing capacity (ozone concentration), and gaseous pollutants (NOx and SO2) correlated with amines under different pollution conditions. Under high RH, acid-base reactions were the dominant pathway for the gas-to-particle distribution of amines in urban areas, while direct dissolution dominated in the background site. To our knowledge, this study is the first attempt to conduct in situ measurements of particulate amines during different pollution conditions in China, and further research is needed to in-depth understanding of the influence of amines on haze formation.