AEROSOL CARBON IN THE DENVER AREA IN NOVEMBER 1973

Aerosol samples collected at the Rocky Mountain Arsenal during the Brown Cloud month of November 1973 showed an amount of unextractable carbon compatible with the Waggoner-Charlson hypothesis that the Denver Brown Cloud is caused by sub-0.1-μm elemental carbon particles. The unextractable carbon was only a small fraction of the total suspended participates and the extent to which it actually causes the perception of the Brown Cloud is not presently quantifiable. Correlation of carbon with lead showed that at these sites the carbon and lead came from the same source or from sources that were somehow strongly linked. The C/Pb mass ratio was 5.5, which is higher than is ordinarily observed from gasoline-powered vehicles operating on leaded gasoline; the possibility that this unexpected observation may result from the operation of engines at Denver elevation merits further investigation. © 1979.