Article

On the individual exposure from airborne hazardous releases: the effect of atmospheric turbulence.

University of Western Macedonia, Department of Engineering and Management of Energy Resources, Sialvera & Bakola Str., 50100 Kozani, Greece.
Journal of Hazardous Materials (Impact Factor: 4.33). 02/2008; 150(1):76-82. DOI: 10.1016/j.jhazmat.2007.04.078
Source: PubMed

ABSTRACT One of the key problems in coping with deliberate or accidental atmospheric releases is the ability to reliably predict the individual exposure during the event. Furthermore, for the implementation of countermeasures, it is essential to predict the maximum expected dosage and the exposure time within which the dosage exceeds certain health limits. Current state of the art methods, which are based on the concentration cumulative distribution function (cdf) and require the knowledge of the concentration variance and the intermittency factor, have certain limitations especially when the exposure time becomes comparable with the peak spectral time. The proposed method aims at estimating maximum dosage as a function of the exposure time, mean concentration and the turbulence integral time scale. It is much simpler than the cdf models and it poses no restrictions on the exposure time length. One of the important consequences is that it can broaden the capability of the ensemble average computational models to estimate maximum dosage for any exposure time. The method has been tested successfully utilizing the ammonia field experiments FLADIS T16 and T17.

0 Bookmarks
 · 
80 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: One of the key problems in coping with deliberate or accidental atmospheric releases is the ability to reliably predict the individual exposure during the event. Due to the stochastic nature of turbulence, the instantaneous wind field at the time of the release is practically unknown. Therefore for consequence assessment and countermeasures application, it is more realistic to rely on maximum expected dosage rather than actual one. Recently Bartzis et al. (2007), have inaugurated an approach relating maximum dosage as a function of the exposure time, concentration mean and variance and the turbulence integral time scale. Such approaches broaden the capability of the prediction models such as CFD models to estimate maximum individual exposure at any time interval. In the present work a further insight is given to this methodology and an alternative correlation is proposed based on theoretical considerations. The methodology to utilize such correlation types is further justified.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Plume dispersion of hazardous materials within urban area resulting from accidental or intentional releases is of great concern to public health. Many researchers have developed local-scale atmospheric dispersion models using building-resolving computational fluid dynamics. However, an important issue is encountered when determining a reasonable domain size of the computational model in order to capture concentration distribution patterns influenced by urban surface geometries. In this study, we carried out Large-Eddy Simulations (LES) of plume dispersion within various urban areas with a wide range of obstacle density and building height variability. The difference of centerline mean and r.m.s. concentration distributions among various complex urban surface geometries becomes small for downwind distances from the point source greater than 1.0 km. From these results, it can be concluded that a length of a computational model should be at least 1.0 km from a point source.
    Advances in Science and Research. 02/2013;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Polymer nanoparticles within the range of 2–5nm with a solid content of more than 13wt.% and a narrow molecular weight polydispersity (Mw/Mn∼1.1) were for the first time prepared using a micellar nucleation differential microemulsion polymerization system emulsified by sodium dodecyl sulfate (SDS), with SDS/monomer (methyl methacrylate) and SDS/H2O weight ratios of up to 1:16 and 1:100, respectively. It was found that for benzoyl peroxide (BPO), micellar nucleation is more favorable for the synthesis of smaller polymer nanoparticles than ammonium persulfate (APS) which gives rise to homogeneous nucleation and 2,2′-azobisisobutyronitrile (AIBN) which involves partially heterogeneous nucleation. In the polymerization process, there exists a critical stability concentration (CSC) of SDS, above which the size of the nanoparticles is to be minimized and stabilized. With an increase in the monomer addition rate, the polymerization system changes from a microemulsion system to an emulsion system. A mechanism was proposed to describe the micellar nucleation process of differential microemulsion polymerization. This study may contribute to the development of fine polymer nanoparticles for drug delivery systems.
    European Polymer Journal - EUR POLYM J. 01/2011; 47(5):973-980.