Characterizing Emerging Sources of Organic Aerosol

城市活动向大气中排放许多有机化合物。它们的化学反应形成颗粒物，导致空气质量差，危害人体健康。由于机动车辆通常被认为是污染物的主要来源，过去几十年的法规集中在控制车辆排放上，从而减少了空气污染。然而，未来的空气质量将越来越依赖于其他重要的颗粒物来源，如烹饪食物、野火和采用新技术的汽车发动机。在这个研究项目中，我们识别新出现的空气污染源排放的有机化合物，并研究它们在大气中的化学反应。必须了解这些来源，以便预测它们对空气质量的影响，并制定具有成本效益的控制战略，以保障公众健康。

Urban activities emit many organic compounds into the atmosphere. Their chemical reactions form particulate matter which contributes to poor air quality and harms human health. Since motor vehicles have usually been identified as the main source of pollutants, regulations in the past decades have focused on controlling vehicular emissions, leading to reductions in air pollution. Future air quality, however, will depend increasingly on other important sources of particulate matter, such as food cooking, wildfires, and vehicular engines with new technologies. In this research program, we identify organic compounds emitted from emerging sources of air pollution and study their chemical reactions in the atmosphere. It is essential to understand these sources in order to predict their impacts on air quality and develop cost-effective control strategies to safeguard public health. Wildfires are becoming more common as a result of a warming climate. Particulate matter from wood burning is known to be harmful for human health, because it contains free radical species that cause damage to the body. With advanced instrumentation we will measure the level of these free radical species in wood smoke, and identify their chemical structures in order to understand the molecular processes that lead to their formation, and their effects on human health. Food cooking emits a large amount of particles in cities, but researchers have typically assumed that these particles readily evaporate in the atmosphere and therefore do not expect them to be important. However, there is little knowledge about evaporation of organic particles, particularly those that have been exposed to the atmosphere for a long time. We will study these atmospheric reactions that prevent particles from evaporating. From our experiments, we will build a mathematical model to describe the evaporation processes and provide computer models with a more accurate way to predict air quality. Engine technologies are rapidly evolving to make them more fuel-efficient, but one such technology, gasoline direct injection, emits more particles that can damage air quality. We will measure organic compounds emitted from these engines and study the chemical reactions that can produce particulate matter. Our measurements will provide a more comprehensive evaluation of how these emerging vehicle technologies will affect air quality and human health. In all research directions, we use detailed chemical measurements to gain fundamental molecular insights, and apply them to understand atmospheric behavior. Through these studies, students gain important scientific and professional skills required for their technical careers. They also work across multiple disciplines (chemistry, engineering, policy, health sciences) and create much needed knowledge to address critical environmental challenges.