The 10th International Aerosol Conference (IAC) is held in St. Louis, which has a rich history of aerosol science and policy. The world’s leading aerosol, climate, energy and nanoparticle researchers gather for IAC once every four years. This year’s event highlights research addressing climate change, renewable energy sources, advances in drug delivery, and improving air quality. Aerosol science and engineering achievements at Washington University in St. Louis is a huge draw for visitors, showcasing the world’s top aerosol and air quality laboratories led by Pratim Biswas, PhD. The conference also sheds light on St. Louis’ air pollution history and how the city handled an air quality crisis now gripping other parts of the world.