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Published December 1, 1975 | public
Journal Article Open

Thermal Analyses of the Los Angeles Smog Aerosol

Abstract

It has been shown by earlier studies on the formation of the Los Angeles smog aerosol, that a significant fraction of the particulate matter in the visible size range is made by secondary gas-particle conversion processes, and that it consists mainly of liquid matter. In this study the volatility was studied quantitatively by heating the smog aerosol up to 250°C and simultaneously measuring the scattering coefficient using a nephelometer and the change of size distribution by an optical counter. The thermal analyses revealed that 50–80% of the submicron aerosol mass is volatile at 220°C. Inspection of the shapes of thermo-nephelograms (bscat vs temperature) also revealed that photochemically formed aerosols have distinctly different thermo-nephelograms than those obtained on humid "hazy" days. Thus it is suggested that thermal analyses may at least in some instances provide the means of on-line monitoring the origin of the ambient aerosol.

Additional Information

© 1975 American Meteorological Society Manuscript received 20February 1975, in revised form 25 July 1975 The authors thank S. K. Friedlander for his illuminating comments. This research was supported by the U. S. Environmental Protection Agency, Division of Chemistry and Physics, Atmospheric Aerosol Research Section, under Grant 800308 and by the California Air Resources Board through contract to Rockwell International, Science Center.

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