Workplace social capital and co-occurrence of lifestyle risk factors: the Finnish Public Sector Study

Objective: The aim of this prospective study was to examine the link between individual and ecological workplace social capital and the co-occurrence of adverse lifestyle risk factors such as smoking, heavy drinking, physical inactivity and overweight.

Work-place social capital and smoking cessation: The Finnish Public Sector Study

AIMS:
To examine whether high social capital at work is associated with an increased likelihood of smoking cessation in baseline smokers.
DESIGN:
Prospective cohort study.
SETTING:
Finland.
PARTICIPANTS:
A total of 4853 employees who reported to be smokers in the baseline survey in 2000-2002 (response rate 68%) and responded to a follow-up survey on smoking status in 2004-2005 (response rate 77%).
MEASUREMENTS:
Work-place social capital was assessed using a validated and psychometrically tested eight-item measure. Control variables included sex, age, socio-economic position, marital status, place of work, heavy drinking, physical activity, body mass index and physician-diagnosed depression.
FINDINGS:
In multi-level logistic regression models adjusted for all the covariates, the odds for being a non-smoker at follow-up were 1.26 [95% confidence interval (CI)=1.03-1.55] times higher for baseline smokers who reported high individual-level social capital than for their counterparts with low social capital. In an analysis stratified by socio-economic position, a significant association between individual-level social capital and smoking cessation was observed in the high socio-economic group [odds ratio (OR) (95% CI)=1.63 (1.01-2.63)], but not in intermediate [(OR=1.10 (0.83-1.47)] or low socio-economic groups [(OR=1.28 (0.86-1.91)]. Work unit-level social capital was not associated with smoking cessation.
CONCLUSIONS:
If the observed associations are causal, these findings suggest that high perceived social capital at work may facilitate smoking cessation among smokers in higher-status jobs.

Low workplace social capital as a predictor of depression - The Finnish public sector study

In a prospective cohort study of Finnish public sector employees, the authors examined the association between workplace social capital and depression. Data were obtained from 33,577 employees, who had no recent history of antidepressant treatment and who reported no history of physician-diagnosed depression at baseline in 2000-2002. Their risk of depression was measured with two indicators: recorded purchases of antidepressants until December 31, 2005, and self-reports of new-onset depression diagnosed by a physician in the follow-up survey in 2004-2005. Multilevel logistic regression analysis was used to explore whether self-reported and aggregate-level workplace social capital predicted indicators of depression at follow-up. The odds for antidepressant treatment and physician-diagnosed depression were 20-50% higher for employees with low self-reported social capital than for those reporting high social capital. These associations were not accounted for by sex, age, marital status, socioeconomic position, place of work, smoking, alcohol use, physical activity, and body mass index. The association between social capital and self-reported depression attenuated but remained significant after further adjustment for baseline psychological distress (a proxy for undiagnosed mental health problems). Aggregate-level social capital was not associated with subsequent depression.

Techno-Economic Feasibility of Selective CO2 Capture Processes from Biogas Streams using Ionic Liquids as Physical Absorbents

Biogas from anaerobic digestion of sewage sludge is a renewable resource with high energy content, which is formed mainly of CH4 (40-75 vol.%) and CO2 (15-60 vol.%) Other components such as water (H2O, 5-10 vol.%) and trace amounts of hydrogen sulfide and siloxanes can also be present. A CH4-rich stream can be produced by removing the CO2 and other impurities so that the upgraded bio-methane can be injected into the natural gas grid or used as a vehicle fuel. The main objective of this paper is to develop a new modeling methodology to assess the technical and economic performance of biogas upgrading processes using ionic liquids which physically absorb CO2. Three different ionic liquids, namely the 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, 1-hexyl-3-methylimidazoliumbis[(trifluoromethyl)sulfonyl]imide and trihexyl(tetradecyl)phosphonium bis[(trifluoromethyl)sulfonyl]imide, are considered for CO2 capture in a pressure-swing regenerative absorption process. The simulation software Aspen Plus and Aspen Process Economic Analyzer is used to account for mass and energy balances as well as equipment cost. In all cases, the biogas upgrading plant consists of a multistage compressor for biogas compression, a packed absorption column for CO2 absorption, a flash evaporator for solvent regeneration, a centrifugal pump for solvent recirculation, a pre-absorber solvent cooler and a gas turbine for electricity recovery. The evaluated processes are compared in terms of energy efficiency, capital investment and bio-methane production costs. The overall plant efficiency ranges from 71-86 % whereas the bio-methane production cost ranges from £6.26-7.76 per GJ (LHV). A sensitivity analysis is also performed to determine how several technical and economic parameters affect the bio-methane production costs. The results of this study show that the simulation methodology developed can predict plant efficiencies and production costs of large scale CO2 capture processes using ionic liquids without having to rely on gas solubility experimental data.