The evolution of aerosol size distributions growing by gas-to-particle conversion has been observed recently in field and laboratory studies. A technique for extracting particle diameter growth rates from such data is presented. The functional dependence of these growth rates on particle diameter (i.e. the growth law) is then examined to infer clues about possible chemical mechanisms of gas-to-particle conversion. The data are consistent with the conclusion that droplet phase (heterogeneous) reactions were important in the Great Smoky Mountains where relative humidities were high (r.h.>75%), while gas phase reactions were the predominant mechanism in smog chamber experiments (r.h.∼-35%).
Bibliographical noteFunding Information:
._(clinouk~,dyc~ntenrs-Thsitsu dy was supported by U.S. Environmental Protection Agency grants No. R803851 and CR806801-01. 14’. E. Wilson. Jr., Project Otlicer. The contents of this paper do not necessarily reflect the views or policies of the Environmental Protection Agency.