This international conference will provide a technical forum on advances in the scientific understanding of the effects of aerosols on urban, regional, continental, and global-scale haze and the radiative balance. The conference will take a multipronged approach by encouraging scientific dailogue (e.g., related to measurements, modeling) as well as including presentations addressing regulatory and policy issues. New topics added for 2020 include sessions on biomass burning and the effects of wildfire, including fire behavior and forecasting, impacts on visibility, radiative balance and health, and possible mitigation strategies. Sessions will be added related to the increasing concerns of the effects of atmospheric nitrogen and carbonaceous material on haze, climate change, and nitrogen deposition on ecosystems.