CHEMISTRY

This examination of the various methods now available to relate ambient oxidant to emissions, discusses briefly, the chemical and physical mechanisms by which emissions are dispersed in the atmosphere, get transported and react to form urban, suburban and nonurban oxidant. The chemical process that occurs when hydrocarbon (HC) and nitrogen oxides (NOX) in air are irradiated by sunlight are detailed, and comment is made on the oxidant plume mechanism which describes the relation between the emission source area and receptor area. Four alternative methods for relating air quality to emissions are presented: namely, rollback formula in conjunction with a simple proportionality relation; use of rollback formulas in conjunction with oxidant-precursor relations derived from smog chamber data; use of detailed mathematical expressions for the dispersion process in conjunction with expressions for the photochemical processes; and statistically support empirical relations either between early-in-the- morning precusor levels and oxidant or between emission rates and oxidant within a given area. Process for the quantification of the precursor emissions (a) dispersion process and (b) the photo chemical reaction process are presented (in an appendix) and critically examined. The role of nitrogen oxides and of natural emissions in urban and nonurban oxidant problems is discussed.

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    • Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved. Presented at the Conference on the State of the Art of Assessing Transportation-Related Air Quality Impacts, Washington, D.C., October 22-24, 1975.
  • Corporate Authors:

    Transportation Research Board (TRB)

    Washington, DC   
  • Authors:
    • Dimitriades, Basil
  • Conference:
  • Publication Date: 1976

Media Info

  • Media Type: Digital/other
  • Features: Figures; References;
  • Pagination: pp 8-20
  • Monograph Title: Assessing transportation-related air quality impacts
  • Serial:

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Filing Info

  • Accession Number: 00139648
  • Record Type: Publication
  • Files: TRIS, TRB, ATRI
  • Created Date: Sep 21 1976 12:00AM