Aerosol physical properties

Standardized long-term measurements provide reliable information on statistical behavior of atmospheric aerosols, far beyond what could be obtained in short-term campaign-wise measurements. Although data from a period of only two years is shown, the results already provide a previously unavailable variety of information on the sub-micron aerosol physical properties and variability in Europe. Such information would also be hard to achieve based on information collected from separately managed stations, especially if the instrumentation and data handling are not harmonized. 

Aerosol physical properties mass, distribution spectra of aerosol particle size, Lidar ratio. 

In the United States, use of CEC propeUants, designated as PropeUants 11, 12, and 114, is strictly limited to specialized medicinal aerosol products such as metered-dose inhalers. The physical properties and chemical names of these propeUents are given in Table 2. 

In the last several decades, physical properties of vaginal contraceptive formulations have been improved to deUver spermicide more effectively and enhance consumer compliance. The formulation that deUvers the spermicide can affect the efficacy of vaginal contraceptives (86,87). Formulations currentiy available include jeUies, creams, suppositories, aerosol foams, and foaming tablets. Each consists of a relative inert base material that serves as a carrier for the chemically active spermicide and blocks to some extent the passage of sperm. 

Atmospheric aerosols have a direct impact on earth s radiation balance, fog formation and cloud physics, and visibility degradation as well as human health effect[l]. Both natural and anthropogenic sources contribute to the formation of ambient aerosol, which are composed mostly of sulfates, nitrates and ammoniums in either pure or mixed forms[2]. These inorganic salt aerosols are hygroscopic by nature and exhibit the properties of deliquescence and efflorescence in humid air. That is, relative humidity(RH) history and chemical composition determine whether atmospheric aerosols are liquid or solid. Aerosol physical state affects climate and environmental phenomena such as radiative transfer, visibility, and heterogeneous chemistry. Here we present a mathematical model that considers the relative humidity history and chemical composition dependence of deliquescence and efflorescence for describing the dynamic and transport behavior of ambient aerosols[3]. 

Methane, See also Liquefied natural gas Natural gas, 41, 47, 258, 291, 484 physical properties, 295 vapour pressure, 294 Micro-organisms, 1, 138 Mineral acids, 27, 28 Mineral oils, 15, 159, 166 Mists, See also Aerosols definition, 14 origin, 51... 

McKay C. P., Coustenis A., Samuelson R. E. et al. (2001). Physical properties of the organic aerosols and clouds on Titan. Planetary and Space Science 49 79. 

Agnew, J.E. (1984). Physical properties and mechanisms of deposition of aerosols. In Aerosols and the Lung, Clinical Aspects (Clarke, S.W. and Pavia, D., Eds.). Butterworth, London, pp. 49-68. 

A study by S.C. Soderholm of the University of Rochester is in progress to relate the deposition efficiency of volatile aerosols of disulfoton in humans to physical properties of the airborne system,... 

The contribution of the various classes of hydrocarbons to the formation of particulate organic compounds is a complex function of their relative ambient concentrations, gas-phase reactivity, and ability to form products whose physical properties, especially vapor pressures, are of prime importance in the physical mechanisms controlling the gas-to-aerosol conversion process. In view of the results discussed previously, cyclic olefins appear to be the most important class of organic aerosol precursors. This is due to their high gas-phase reactivity and their ability... 

Finally, receptor modeling offers a useful theme around which to organize aerosol characterization studies. Large scale field studies are expensive, and they also tend to be diffuse. Data requirements for source resolution can be used to select the chemical and physical properties of the aerosol to be measured both at receptor sites and at sources. 

Quinn, P. K., D. S. Covert, T. S. Bates, V. N. Kapustin, D. C. Ranisey-Bell, and L. M. Mclnnes, Dimethylsulfide Cloud Condensation Nuclei Climate System Relevant Size-Resolved Measurements of the Chemical and Physical Properties of Atmospheric Aerosol Particles, J. Geophys. Res., 98, 10411-10427 (1993). 

Li, S.-M., K. B. Strawbridge, W. R. Leaitch, and A. M. Macdonald, Aerosol Backscattering Determined from Chemical and Physical Properties and Lidar Observations over the East Coast of Canada, Geophys. Res. Lett., 25, 1653-1656 (1998). 

Fujitani, Y., Kobayashi, T., Arashidani, K., Kunugita, N. and Suemura, K. (2008) Measurement of the physical properties of aerosols in a fullerene factory for inhalation exposure assessment /. Occup. Environ. Hyg., 5 (6), 380-389. 

PERSONAL MONITORING IS A RELATIVELY NEW CONCEPT in community air pollution measurement research (1-3). This fact is not surprising because most air pollution investigations have been directed toward the characterization of the ambient atmosphere, the observation of pollutant trends, the acquisition of data on chemical kinetic parameters and on the physical properties of aerosols, and the determination of compliance to national and other standards (4). Before the late 1970s, research on personal monitors was primarily conducted in industrial settings (5, 6) because American Confer-... 

The most often measured property of the LRT wildfire smokes is the mass concentration of aerosol particles in fine (PM2.5) or submicron (PMi) or in fine and coarse size fraction together (PM10). The mass concentration is usually determined either with a tapered element oscillating microbalance (e.g., [19]), or with the instruments based on p-attenuation (e.g., [13]). In addition to mass concentration, real-time instruments can measure other physical properties of particles, e.g., number concentration of particles in different size fractions using a differential mobility particle sizer [13] or the optical characteristics of smoke by a nephelometer [32]. Ground-based instruments also include remote sensing instruments such as sun photometers [32],... 

Again the chemical/physical properties of the analytes will determine the collection and reconstitution rinse parameters. During the extraction step, the volatility of the analytes will determine the collection temperature or type of adsorbent material used for collection. If the analytes are volatile, then a cold trap or cooled collection solvent along with a low flow rate should be used. This is because the analytes are volatile and the expansion of the C02 can create aerosols or mechanically move the analytes past the collection device. Less volatile analytes can tolerate higher extraction flow rates and higher collection temperatures can be used. If an adsorbent trap is used for collection, the chemist can specifiy an appropriate adsorbent and rinse solvent for optimal recoveries for the analytes of interest. Flow rate and volume are parameters that also need to be specified. The flow rate and rinse volume are determined by the solublity of the analytes in the rinse solvent and the amount of material to be removed from the trap. 

In this chapter, we made an attempt to provide a comprehensive review of the current state-of-the-art on sources, chemical nature, and physical properties of organic aerosols. This review begins with an overview of few basic concepts on atmospheric aerosols, followed by a description of the major constituents of atmospheric aerosols. The sources, transformations, and removal processes of organic aerosols are outlined and followed by an overview of the major environmental and human health issues associated with organic aerosols. The chemical and physical characterization of organic aerosols is then reviewed and is finally followed by a list of uncertainties and suggestions that require further studies. 

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