OpenAQ is the largest, open source air quality data platform, hosting 5+ billion real-time and historical measurements from 120 countries, and serving an average of 35 million API requests per month. The data have been used for a wide variety of applications, from air quality forecasts produced by NASA scientists to platforms communicating air quality in India to data-driven media reports by the general public. By providing this foundational data infrastructure, OpenAQ is able to convene people and organizations from across the globe to further raise awareness and develop innovative solutions to combat air pollution. The talk will give a technical overview of the platform, highlight the impact through user stories, and feature new tools developed with the community to enhance the platform and effectively use the data to fight for clean air.