Understanding the Hygroscopic Properties of Black Carbon/Organic Carbon Mixing States: Connecting Climate and Health Impacts of Anthropogenic Aerosol

EPA Grant Number: R835040
Title: Understanding the Hygroscopic Properties of Black Carbon/Organic Carbon Mixing States: Connecting Climate and Health Impacts of Anthropogenic Aerosol
Investigators: Asa-Awuku, Akua
Institution: University of California - Riverside
EPA Project Officer: Chung, Serena
Project Period: October 1, 2011 through September 30, 2014 (Extended to September 30, 2016)
Project Amount: $449,925
RFA: Black Carbon's Role In Global To Local Scale Climate And Air Quality (2010) RFA Text |  Recipients Lists
Research Category: Global Climate Change , Climate Change , Air


The hypothesis of the proposed work is as follows: If black carbon (BC) is well mixed with organic hygroscopic material, it will significantly alter droplet growth rates and sizes. This will impact droplet deposition rates in the lungs and influence radiative forcing estimates of the aerosol-indirect effect. Five strategic objectives will test the proposed theory.


The PI will: 1) design a novel apparatus to control and modify BC/OC aerosol mixing states for subsequent testing; 2) identify unique and viable on-line and off-line measurement techniques to characterize BC/OC water-uptake and droplet growth; 3) test the ability to promote the water-uptake ability of BC containing particles by exploring changes in particle ageing and hygroscopic behavior in the presence of common air pollutants (NOx and O3); 4) measure the in-situ cloud droplet ability of BC diesel engine emissions from diesel engine and biodiesel fuel blends; and, 5) apply experimental results to droplet growth models to quantify the impact of BC on climate and health.

A suite of online and off-line measurements will quantify BC and OC fractions and a CCN counter will measure the aerosol droplet forming potential. The PI will study the effect of BC/OC mixing states on droplet growth rates. The expected results will be used to explore the impact of BC/OC for the aerosol-indirect effect and probe the impacts on health (specifically, BC respiratory deposition rates). The proposed research addresses two of the four EPA “specific research areas of interest/expected outputs and outcomes” topics. The success of the project will improve our understanding of BC sources, aerosol chemical composition, physical properties, and quantities of BC, related co-pollutants (EPA-1) in the context of the impacts of long range transport of BC and their effect on air quality and regional climate forcing (EPA-3).

Expected Results:

Results from a successful completion of the proposed work will aid in the risk assessment and management of BC from traffic-related sources. The proposed work will also address possible impacts of the use of alternative fuel sources in engine.

Publications and Presentations:

Publications have been submitted on this project: View all 34 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 9 journal articles for this project

Supplemental Keywords:

atmospheric pollution, black carbon, climate, aerosol-indirect effect, tropospheric aerosol, droplet growth, health, mixing state, particle hygroscopicity,

Progress and Final Reports:

  • 2012 Progress Report
  • 2013 Progress Report
  • 2014 Progress Report
  • 2015 Progress Report
  • Final Report