Hygroscopic particles

FOG (mists) Liquid aerosols formed either by condensation of a liquid on particulate nodes in air or by uptake of liquid by hygroscopic particles. 

Hygroscopic Particle Deposition Determined by Initial MMAD... 

Particle size is a major factor which determines the alpha dose conversion factor for radon daughters (mGy/WLM). Data on indoor environments are emerging and indicate that a variety of specific conditions exist. For example, a dose factor four times that for a nominal occupational or environmental exposure exists if kerosene heater particles dominate the indoor aerosol and four times smaller if a hygroscopic particle dominates. 

It is important to update the bronchial dosimetry for radon daughters as new information becomes available. It is the purpose of this study to show that there is a potential for either significantly increased bronchial dose in the home per unit exposure if the ambient particle size is artificially reduced due, for example, to open-flame burning or use of kerosene heaters, or a decreased dose if hygroscopic particles dominate the indoor aerosol. 

Tu and Knutson (1984) also measured the particle deposition of hydrophobic and hygroscopic particles in the human respiratory tract. They showed that the hygroscopic particles grow by a factor of 3.5 to 4.5 at the saturated humidity present in the lung. For the purpose of calculating bronchial deposition for a hygroscopic aerosol we assume an increase in size by a factor of 4 upon entry into the bronchial tree. 

Different. Nominal calculation for mine and home but adding calculations which include kerosene heater particles and hygroscopic particles. (Tu et al., 1985)... 

The presence of water does not only create conditions for the existence of an electrolyte, but it acts as a solvent for the dissolution of contaminants [10], Oxygen plays an important role as oxidant element in the atmospheric corrosion process. The thickness of the water layer determines the oxygen diffusion toward the metallic surface and also the diffusion of the reaction products to the outside interface limited by the atmosphere. Another aspect of ISO definition is that a metallic surface is covered by adsorptive and/or liquid films of electrolyte . According to new results, the presence of adsorptive or liquid films of electrolyte perhaps could be not in the entire metallic surface, but in places where there is formed a central anodic drop due to the existence of hygroscopic particles or substances surrounded by microdrops where the cathodic process takes place. This phenomenon is particularly possible in indoor conditions [15-18],... 

A factor of note is (he settling and adherence of panicles on metals. Particles of carbon, ammonium sulfate, and silica cause a marked increase in corrosion, und this is accentuated in atmospheres containing sulfur dioxide. The presence of such hygroscopic particles enhances the adherence of liquid and thus provides lor electrochemical attack. 

Hygroscopic particles grow as water vapour is condensed on them as they pass down the respiratory tract. Tu Knutson (1989) found 50% deposition of 0.35- m NaCl particles inhaled orally. Minimum deposition of NaCl was found at a particle size of 0.075 jum. 

Lee C.-T. and Hsu W.-C. (2000) The measurements of liquid water mass associated with collected hygroscopic particles. 

Martonen TB. Analytical model of hygroscopic particle behavior in human airways. Bull Math Biol 1982 44 425-442. 

Chemical Properties of Aerosols. Surface chemical properties of aerosol particles can also be tailored to improve deaggregation [273]. Hygroscopic particles absorb water when inhaled into the humid airways [282-284], increasing particle size and density in the process, as well as creating the potential for capillary bridge formation between particles. Hygroscopic growth can be reduced by the use of hydrophobic additives [285] or compounds with low aqueous solubility [286,287]. 

Panicle huental Pressure Laplace s Formula 257 Limit of Applicability of Kelvin Relation 258 Hygroscopic Particle-Vapor Equilibrium 259 Charged Particle-Vapor Equilibria 263 Solid-Particle-Vapor Equilibrium 265... 

Figure 15. The influence of inhaled particle size and breathing mode on ammonium sulphate aerosol deposition (—) non-hygroscopic particle behaviour included for comparison minute volume = 30 1. RH = relative humidity Reproduced with permission from Martonen TB (1985). Ambient sulphate deposition in man modelling the influence of hygroscopicity. Environmental Health Perspectives, 63, 11-24...

This figure shows the mass deposition fraction plotted against the initial geometric particle size. Martonen et al (1985) argued that a critical particle size could be defined Dc. For hygroscopic particles initially smaller than this size, hygroscopic growth would be expected to reduce... 

Figure 16. Total and regional distribution of hygroscopic particles in the lung. Oral breathing tidal volume, 500 ml breathing rate, 13.7 breaths per minutes. 1, non-hygroscopic 2, hygroscopic. Solid line, total deposition dotted line, deposition in pulmonary region dashed line, deposition in tracheobronchial region. Reproduced from Pritchard JN (1987). Particle growth in the airways and the influence of airflow. In A New Concept in Inhalation Therapy (SP Newman, F Moren and GK Crompton, eds), Medicom...

Figure 19.2 shows deposition velocity data for particles as a function of particle size for a water surface in a wind tunnel. Zufall et al. (1999) have shown that deposition to bodies of water exposed to the atmosphere can have as much as double the deposition velocity compared to a flat water surface owing to the presence of waves. Furthermore, growth of hygroscopic particles in the humid boundary layer just above the air-water interface can increase deposition velocities slightly compared with deposition to dry surfaces (Zufall et al. 1998). 

Although recognized for hundreds of years, artificial weather modification was not applied before the turn of the 20 century. It started by simply introducing artificial CCN to the cloud layers by guns, later rockets and aircrafts. By end of the 1940s the introduction of crystallization nuclei (e. g. Agl, dry ice and many others) affected the ice phase processes in supercooled clouds and larger hygroscopic particles (artificial precipitation embryos about 30 pm in diameter) to stimulate collision-coalescence processes in warm clouds. About 10 countries applied different techniques with variable success. 

Hygroscopic Particle specific gravity Adhesion Corrosiveness... 

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