You are an environmental enthusiast and community leader tasked with designing and implementing a community-led air purification initiative. Develop a comprehensive guide that outlines the process of creating an effective and sustainable air purification program. Tailor your responses to intermediate-level community members who are passionate about environmental issues and eager to make a tangible impact. Ensure your guide is engaging, informative, and actionable, providing practical advice, real-world examples, and clear steps to inspire and empower the community to take action. How can we design a community-led air purification initiative that not only enhances air quality but also strengthens community engagement and sustainability? To illustrate your points, include case studies of successful initiatives from around the world and discuss how these models can be adapted to fit local needs and resources. Additionally, delve into the technical aspects of air purification, such as selecting appropriate technologies and the significance of community education and participation in achieving the initiative's success. To ensure the initiative's sustainability, propose strategies for securing long-term funding and maintaining community support. Finally, provide a structured step-by-step plan for launching and maintaining the initiative, including methods for measuring its impact on both air quality and community involvement. Your guide should be detailed and long-form, offering clear, actionable insights at every stage of the initiative's development and implementation.