Formation of Urban Ultrafine Particles in Houston

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This project focuses on atmospheric processes that can lead to the formation of urban ultrafine particles in the urban atmosphere. Understanding the formation of ultrafine particles is important because they have higher penetration and deposition efficiencies in the lung and have higher toxicity than larger particles. They can also enhance the production of cloud condensation nuclei. This research is relevant for better understanding climate and air quality issues, particularly in urban areas.Two 6-week field campaigns are planned for measuring chemical precursors such as highly oxygenated molecules, and particle sizes and chemical composition with a suite of state-of-the-art aerosol and chemical instrumentation. The field work will be conducted in the metropolitan Houston area due to the variety of emissions for aerosol and gas-phase precursors from oil refineries, power plants, ship channels, urban and marine emissions in the region. The main scientific questions to be addressed are: (1) What is the relative contribution of traffic emissions vs. new particle formation to the urban ultrafine particles in Houston? (2) What is the molecular composition of urban HOMs (highly oxygenated organic molecules) under different temperatures and NOx (NO+N02) conditions? (3) How is urban new particle formation facilitated by different chemical precursors, such as sulfuric acid, ammonia, amines, and HOMs in Houston? This research will support two female faculty members and several graduate students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.