Polycyclic aromatic hydrocarbon (PAH) emissions from a coal-fired pilot FBC system

Due to the extensive amount of data suggesting the hazards of these compounds, 16 polycyclic aromatic hydrocarbons (PAHs) are on the Environmental Protection Agency (EPA) Priority Pollutant List. Emissions of these PAHs in the flue gas from the combustion of four coals were measured during four 1000h combustion runs using the 0.1MW heat-input (MWth) bench-scale fluidized bed combustor (FBC). An on-line sampling system was designed for the 16 PAHs, which consisted of a glass wool filter, condenser, glass fiber filter, Teflon filter, and a Tenax trap. The filters and Tenax were extracted by methylene chloride and hexane, respectively, followed by GC/MS analysis using the selective ion monitoring (SIM) mode. In this project, the effects of operating parameters, limestone addition, chlorine content in the coal, and Ca/S molar ratio on the emissions of PAHs were studied. The results indicated that the emissions of PAHs in an FBC system are primarily dependent on the combustion temperature and excess air ratio. The injection of secondary air with high velocity in the freeboard effectively reduces PAH emissions. The addition of extra limestone can promote the formation of PAHs in the FBC system. Chlorine in the coal can possibly lead to large benzene ring PAH formation during combustion. The total PAH emission increases with an increase in the sulfur content of coal. Incomplete combustion results in PAHs with four or more benzene rings. High efficiency combustion results in PAHs with two or three benzene rings.     

Dynamic behavior of semivolatile organic compounds in indoor air. 2. Nicotine and phenanthrene with carpet and wallboard

The surface interactions of nicotine and phenanthrene with carpet, painted wallboard, and stainless steel were investigated in a room-sized environmental test chamber. Adsorption kinetics were tested by flash evaporating a known mass of each compound into a sealed 20 m3 chamber containing one or more of the tested sorbents. In each experiment, one or more emissions were performed after the gas-phase concentration had reached an apparent plateau. At the end of each experiment, the chamber was ventilated and resealed to monitor reemission of the compound from the sorbents. Kinetic sorption parameters were determined by fitting a mass-balance model to the experimental results. The sorption capacity of stainless steel was of similar magnitude for nicotine and phenanthrene. Sorption of nicotine on carpet and wallboard was much stronger, with equilibrium partitioning values 2-3 orders of magnitude higher. The sorption capacities of phenanthrene on carpet and wallboard were smaller, approximately 10-20% of the stainless steel values. The rates of uptake are of similar magnitude for all sorbate--sorbent pairs and are consistent with the limit imposed by gas-phase boundary-layer mass transport. The rates of desorption are much faster for phenanthrene than for nicotine. Model simulations predict average nicotine levels in a typical smoking residence that are consistent with published data.     

Resources for health: A primary-care-based diet and physical activity intervention targeting urban Latinos with multiple chronic conditions.

Objective: The Resources for Health trial evaluates a social-ecologically based lifestyle (physical activity and diet) intervention targeting low-income, largely Spanish-speaking patients with multiple chronic conditions. Design: A randomized controlled trial was conducted with 200 patients recruited from an urban community health center and assigned to intervention and usual care conditions. Intervention involved 2 face-to-face, self-management support and community linkage sessions with a health educator, 3 follow-up phone calls, and 3 tailored newsletters. Main Outcome Measures: Primary outcomes measured at 6-months were changes in dietary behavior and physical activity. Changes in multilevel support for healthy living were evaluated as a secondary outcome. Results: After adjustment for age, sex, language, and number of chronic conditions, significant intervention effects were observed for dietary behavior and multilevel support for healthy lifestyles but not for physical activity. Conclusion: The Resources for Health intervention provides an effective and practical model for improving health behavior among low-income, Spanish-speaking patients with multiple chronic conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parallelisation of the Lagrangian atmospheric dispersion model NAME

The NAME  Atmospheric Dispersion Model is a Lagrangian particle model used by the Met Office to predict the propagation and spread of pollutants in the atmosphere. The model is routinely used in emergency response applications, where it is important to obtain results as quickly as possible. This requirement for a short runtime and the increase in core number of commonly available CPUs, such as the Intel Xeon series, has motivated the parallelisation of NAME  in the OpenMP  shared memory framework. In this work we describe the implementation of this parallelisation strategy in NAME  and discuss the performance of the model for different setups. Due to the independence of the model particles, the parallelisation of the main compute intensive loops is relatively straightforward. The random number generator for modelling sub-grid scale turbulent motion needs to be adapted to ensure that different particles use independent sets of random numbers. We find that on Intel Xeon X5680 CPUs the model shows very good strong scaling up to 12 cores in a realistic emergency response application for predicting the dispersion of volcanic ash in the North Atlantic airspace. We implemented a mechanism for asynchronous reading of meteorological data from disk and demonstrate how this can reduce the runtime if disk access plays a significant role in a model run. To explore the performance on different chip architectures we also ported the part of the code which is used for calculating the gamma dose from a cloud of radioactive particles to a graphics processing unit (GPU) using CUDA-C. We were able to demonstrate a significant speedup of around one order of magnitude relative to the serial CPU version.