Christopher J. Hennigan


Associate Professor

Contact Information

Technology Research Center (TRC), Room 253


Postdoctoral Fellow, Center for Atmospheric Particle Studies – Carnegie Mellon University, 2008-2012
Ph.D. Environmental Engineering – Georgia Institute of Technology, 2008
M.S. Environmental Engineering – Georgia Institute of Technology, 2006
B.S. Chemistry – University of Florida, 2001

Research Interests

Our research is centered on issues of air pollution and atmospheric chemistry. A main goal of our work is to understand the sources, transformation, and fate of pollutants in the atmosphere. Our research focuses on a class of pollutants known as particulate matter (PM) or aerosols. These small particles in the air have detrimental impacts on human health and important implications for climate change. Some particles are emitted directly (think tailpipe emissions) into the atmosphere while others form from chemical reactions of gas-phase compounds: our work aims to better understand these formation processes.

Our research is carried out through a combination of atmospheric measurements, laboratory experimentation, and modeling work. We develop and deploy instrumentation to measure in situ aerosol loadings at high time resolution in order to investigate and explain the factors that influence their concentrations in the atmosphere. Based on our atmospheric observations, we also conduct laboratory experiments to characterize specific chemical mechanisms and processes that may be important for aerosols. Finally, we utilize models to both assess the large-scale impacts (continental to global scales) of aerosols on health and climate and to probe our understanding of the processes impacting aerosol concentrations through direct comparison with observations.

Selected Publications – Google Scholar

  1. Pratap, V., Battaglia Jr., M.A., Carlton, A.G., Hennigan, C.J., No evidence for brown carbon formation in ambient particles undergoing atmospherically relevant drying, Environmental Science: Processes & Impacts, 22, 442, (2020).
  2. Hennigan, C. J.; Mucci, A.; Reed, B. E., Trends in PM2.5 transition metals in urban areas across the United States, Environmental Research Letters, 14, 104006, (2019).
  3. Battaglia Jr., M. A., Weber, R. J., Nenes, A., and Hennigan, C. J.: Effects of water-soluble organic carbon on aerosol pH, Atmospheric Chemistry and Physics, 19, 14607–14620,, (2019).
  4. Carlton, A. G., H. O.T. Pye, K. R. Baker, C. J. Hennigan, Additional Benefits of Federal Air-Quality Rules: Model Estimates of Controllable Biogenic Secondary Organic Aerosol, Environmental Science & Technology, 52(16) 9254-9265 (2018).
  5. Battaglia, Jr., M. A.; Douglas, S.; Hennigan, C. J., Effect of the Urban Heat Island on Aerosol pH, Environmental Science & Technology, 51, 13095-13103, (2017).
  6. Valerino, M. J.; Johnson, J. J.; Izumi, J.; Orozco, D.; Hoff, R. M.; Delgado, R.; Hennigan, C. J., Sources and composition of PM2.5 in the Colorado Front Range during the DISCOVER-AQ study, J. Geophys. Res. Atmos., 121, doi:10.1002/2016JD025830 (2017).
  7. El-Sayed, M. M. H.; Amenumey, D.; Hennigan, C. J., Drying-Induced Evaporation of Secondary Organic Aerosol during Summer, Environmental Science & Technology, 50 (7), 3626-3633 (2016).
  8. Hennigan, C. J.; Izumi, J.; Sullivan, A. P.; Weber, R. J.; Nenes, A., A critical evaluation of proxy methods used to estimate the acidity of atmospheric particles, Atmospheric Chemistry and Physics, 15, 2775-2790 (2015).
  9. El-Sayed MMH, Wang Y, Hennigan CJ. Direct atmospheric evidence for the irreversible formation of aqueous secondary organic aerosol. Geophysical Research Letters. 2015;42(13):5577-86. doi: 10.1002/2015gl064556.
  10. Hennigan CJ, Izumi J, Sullivan AP, Weber RJ, Nenes A. A critical evaluation of proxy methods used to estimate the acidity of atmospheric particles. Atmospheric Chemistry and Physics. 2015;15(5):2775-90. doi: 10.5194/acp-15-2775-2015.
  11. Jathar SH, Gordon TD, Hennigan CJ, Pye HO, Pouliot G, Adams PJ, Donahue NM, Robinson AL. Unspeciated organic emissions from combustion sources and their influence on the secondary organic aerosol budget in the United States. Proceedings of the National Academy of Sciences of the United States of America. 2014;111(29):10473-8. Epub 2014/07/09. doi: 10.1073/pnas.1323740111.
  12. Engelhart GJ, Hennigan CJ, Miracolo MA, Robinson AL, Pandis SN. Cloud condensation nuclei activity of fresh primary and aged biomass burning aerosol. Atmospheric Chemistry and Physics. 2012;12(15):7285-93. doi: 10.5194/acp-12-7285-2012.
  13. Hennigan CJ, Miracolo MA, Engelhart GJ, May AA, Presto AA, Lee T, Sullivan AP, McMeeking GR, Coe H, Wold CE, Hao WM, Gilman JB, Kuster WC, de Gouw J, Schichtel BA, Collett JL, Kreidenweis SM, Robinson AL. Chemical and physical transformations of organic aerosol from the photo-oxidation of open biomass burning emissions in an environmental chamber. Atmospheric Chemistry and Physics. 2011;11(15):7669-86. doi: 10.5194/acp-11-7669-2011.
  14. Hennigan CJ, Sullivan AP, Collett JL, Robinson AL. Levoglucosan stability in biomass burning particles exposed to hydroxyl radicals. Geophysical Research Letters. 2010;37(9):n/a-n/a. doi: 10.1029/2010gl043088.
  15. Hennigan CJ, Bergin MH, Russell AG, Nenes A, Weber RJ. Gas/particle partitioning of water-soluble organic aerosol in Atlanta. Atmospheric Chemistry and Physics. 2009;9(11):3613-28. doi: 10.5194/acp-9-3613-2009.
  16. Hennigan CJ, Bergin MH, Dibb JE, Weber RJ. Enhanced secondary organic aerosol formation due to water uptake by fine particles. Geophysical Research Letters. 2008;35(18). doi: 10.1029/2008gl035046.