This is a past event.

Richard C. Flagan

California Institute of Technology

Richard Honrath Memorial Lecture

Particles in the low nanometer size regime are found throughout the atmosphere. Some nanoparticles form in the air when products of atmospheric reactions nucleate to form stable clusters and particles. Atmospheric nucleation is thought to form nearly half of the atmospheric particles globally. Nucleation may also occur when vapors are mixed with cooler air upon exhaust to the atmosphere, possibly contributing to the short-lived nanoparticle concentration excursions near roadways, and the health impacts that have been tenuously linked to them. To understand the health and climate effects of these atmospheric ultrafine particles, we need to measure their abundance and properties, and to understand their dynamics. New measurement methods and ultra-clean reactors now enable direct measurement of new particles soon after their formation under well controlled conditions. To understand the health impacts of airborne nanoparticles, a new paradigm for atmospheric measurements is needed. Ongoing work toward this end will be discussed.