Is carbon dioxide pricing a driver in concrete mix design?

The global cement industry is responsible for 7% of anthropogenic carbon dioxide emissions and, as such, has a vital role to play in the transition to a low carbon dioxide economy. In recent years, this has been achieved by technological advances and increased use of supplementary cementitious materials, but the authors have recently shown that there are other means of achieving comparable carbon dioxide savings, for example, by reducing workability. However, price remains a considerable barrier to the widespread implementation of low carbon dioxide concrete. Using the same model for concrete mix design as was used to determine embodied carbon dioxide (ECD), variations in the cost of the components of concrete have now been considered. Considering 24 different mix designs, each spanning a range of characteristic strengths from 20 to 100 MPa, measures to reduce the carbon dioxide footprint were also found to reduce the material cost of the concrete. As such, it may be considered that the construction industry is already encouraged to reduce its ‘carbon footprint’. However, the concept of the carbon footprint was then considered in a more nuanced fashion, considering the ECD per unit strength. On such a basis, the cheapest mixes did not have the lowest ECD. Therefore, the impact of levying a charge on the carbon footprint was considered. To ensure low carbon dioxide concrete is also the cheapest, carbon dioxide emissions would have to be priced approximately one to two orders of magnitude higher than current market value. This would become the dominant factor in construction, with serious consequences for the industry. Furthermore, such charges may pose ethical problems, being viewed as a ‘licence to pollute’ and therefore undermining society's efforts to reduce the carbon dioxide emissions of the construction industry

Association of objective sedentary behaviour and self-rated health in English older adults

Abstract Objective Reducing sedentary behaviour (SB) might improve the health of older adults. However, we know little about how objectively measured SB impacts on self-rated health in older adults. We aimed to explore the associations between objectively measured SB and self-rated health in English older adults. Results A random sub-sample of older adults (≥ 65 years old) from the 2008 Health Survey for England wore an ActiGraph GT1M accelerometer for 7 days. Self-rated health was measured using an item from the General Health Questionnaire. Linear regression and analysis of covariance were used to test the associations between percentage time spent in SB and mean daily minutes in SB and self-rated health (very good/good; fair; bad/very bad), adjusting for covariates. Valid accelerometry datasets were returned by 578 individuals. Significant negative associations between percentage time and mean daily minutes in SB and self-rated health were found. In particular, individuals spending reduced percentages of time being sedentary had higher self-rated health. In conclusion, SB appears to be associated with self-rated health in older people independently from MVPA. If longitudinal research could determine how changes in SB influence self-rated health as individuals’ age, this might be an important lifestyle variable to target for health improvement

Associations of sedentary behavior and physical activity with psychological distress: a cross-sectional study from Singapore

Background: Emerging evidence suggests the adverse association between sedentary behavior (SB) and physical with mental health, but few studies have investigated the relationship between volume of physical activity and psychological distress. The present study examined the independent and interactive associations of daily SB and weekly level of moderate to vigorous physical activity (MVPA) with psychological distress in a multi-ethnic Asian population. Methods. De-identified data of 4,337 adults (18-79 years old) on sedentary behaviors, physical activity patterns, psychological distresses, and other relevant variables were obtained from the Singapore Ministry of Health's 2010 National Health Survey. Psychological distress was assessed using General Health Questionnaire-12 (GHQ-12), whereas total daily SB and total weekly volume (MET/minutes) of MVPA were estimated using the Global Physical Activity Questionnaire version 2 (GPAQ v2). Multivariate logistic regression analyses were carried out to estimate the odds ratios (95% confidence intervals) of the independent and interactive relationships of SB and MVPA with prevalence of psychological distress. Results: The category of high SB was positively associated with increased odds (OR = 1.29, 1.04-1.59) for psychological distress, whereas the category of active was inversely associated with lower odds (OR = 0.73, 0.62-0.86) for psychological distress. Multivariate analyses for psychological distress by combined daily SB and weekly MVPA levels showed inverse associations between middle SB and active categories (OR = 0.58, 0.45 - 0.74) along with low SB and active categories (OR = 0.61, 0.47-0.80). Conclusions: The present population-based cross-sectional study indicated that in the multi-ethnic Asian society of Singapore, a high level of SB was independently associated with psychological distress and meeting the recommended guidelines for physical activity along with ≤ 5 h/day of SB was associated with the lowest odds of psychological distress