Each particle in the air we breathe has a history. The chemical composition of those particles provides clues to the sources and the potential impacts of those particles on human health and the climate system. Join this lecture with Dr. Peter DeCarlo to explore particle composition in indoor and outdoor spaces to better understand what is in the air we breathe. Dr. Peter DeCarlo is an Associate Professor at Johns Hopkins University in the Department of Environmental Health and Engineering in the Whiting School of Engineering. Dr. DeCarlo has a Ph.D. in Atmospheric Science, and a BS in Biochemistry. He uses state-of-the-art instrumentation to measure the chemical composition of particulates and gases in indoors, outdoors, and in the laboratory to better understand the intersection between energy, air quality, health, and climate impacts of human emissions. He has made air quality and climate related measurements from planes, trucks, and stationary sites all over the world to better understand direct emissions, sources, and subsequent chemical reactions of pollutants in the atmosphere.