Poor air quality has been affecting the Chinese people for many years due to the country’s speedy industrialization and urbanization. However, very few initiatives had been taken by civil society until 2011. The air pollution campaign between October 2011 and March 2012 initiated on a Chinese microblogging website, mobilized millions of citizens and effected policy change. It is often seen as a milestone in the chronology of public participation in China. Using process tracing, participant observations, framing analysis and in-depth interviews, the article analyses this campaign by revealing its major actors and frames mobilizing issue entrepreneurs and environmental publics. Our analysis generates two findings: first, microblogging platforms can greatly expand the networks of Chinese environmental activists by involving public figures and governmental agencies; second, the frame which links air pollution to health and appreciates governmental efforts is critical to the success of civic participation in China’s environmental governance.