Reactive and hazardous organic compounds in the atmosphere have significant impacts on both the environment and human health. Accurately identifying and quantifying the emission sources of RHOCs remains a key challenge. Among these, formaldehyde (HCHO) is a critical compound due to its pivotal role in atmospheric photochemical reactions and its classification as a significant carcinogen. This talk will highlight my key research findings on characterizing real-world HCHO emissions from anthropogenic sources, utilizing a self-developed online measurement system, with a focus on vehicle emissions as a major source. In addition, I will present a framework for identifying and resolving various emission sources of HCHO based on ambient monitoring data. The talk will also provide a preview of planned work addressing broader aspects of reactive and hazardous organic compound emissions.