Abstract
Airborne nanoparticles have been measured for more than a century, but their chemical and physical nature is only now beginning to be understood. Exposures to nanoparticles (particles with diameters smaller than 100 nm) have been linked to a number of adverse respiratory and cardiovascular health effects. Once thought to be rare, the formation of nanoparticles by homogeneous nucleation of the products of atmospheric photochemical reactions has now been observed in both pristine remote locations, and in polluted urban environments. The key to this growing understanding of these small particle is instrumentation that enables rapid measurement of particle size distributions in the low nanometer size range using the scanning electrical mobility spectrometer (also known as the scanning mobility particle size, SMPS). Originally limited to particles larger than about 10 nm, recent advances have enabled measurements down to 1 nm diameter, and made possible measurements of incipient particles. Using these tools, we are probing the formation of particles in atmospheric reactions, and examining the role of atmospheric ions in the nucleation process. To enable rigorous study of the health impacts of airborne nanoparticles, we have developed new instrumental approaches that make it possible to miniaturize instruments for nanoparticle measurement and to develop personal nanoparticle exposure monitors.
About the speaker
Richard Flagan is the McCollum/Cororan Professor of Chemical Engineering, Professor of Environmental Science and Engineering, and Executive Officer for Chemical Engineering at the California Institute of Technology. He received his BS in Mechanical Engineering from the University of Michigan in 1969, and his SM and PhD in Mechanical Engineering from the Massachusetts Institute of Technology in 1971 and 1973, respectively. Upon joining the faculty of Caltech in 1975, Prof Flagan shifted his research focus from the study of gaseous pollutant formation in combustion to the study of aerosols. From an initial investigation of particle formation in coal combustion, his research has expanded into many branches of aerosol science and technology including the development of aerosol reactors for the refining of silicon for photovoltaic applications, nanoparticle synthesis, and microelectronic device fabrication, atmospheric aerosols and their impacts on urban air quality and global climate, and pollen and other allergenic bioaerosols. To facilitate these diverse studies, Prof Flagan has developed instruments ranging from the first low pressure impactor to enable nanoparticle measurements, the scanning mobility particle sizer, and radial differential mobility analyzers that have extended the measurement range down to 1 nm, among others. He has published over 300 scientific papers and 1 book, and holds 18 patents. His research has been recognized with a number of awards, including the Marion Smoluchowski Award of the Gesellschaft fur Aerosolforschung (1990), the David Sinclair Award of the American Association for Aerosol Research (1993), the Thomas Baron Award in Fluid-Particle Systems of the American Institute of Chemical Engineers (1997), the Fuchs Memorial Award presented by the Gesellschaft fur Aerosolforschung, the American Association for Aerosol Research, and the Japan Association for Aerosol Science and Technology (2006), and the American Chemical Society Award for Creative Advances in Environmental Science and Technology (2007). He received a Doctor of Technology honoris causa from Lund University in 2004, and was elected to the US National Academy of Engineering in 2010
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