This paper identifies the diverse ways in which participants engage with science, through the same citizen science project. Using multiple data sources, we describe various activities conducted by citizen scientists in an air quality project, and characterize the motivations driving their engagement. Findings reveal several themes, indicative of participants motivations and engagement; worried residents, education and outreach, environmental action, personal interest and opportunistic engagement. The study further illustrates the interconnectivity between science communication and citizen science practices and calls for nurturing this relationship for the mutual advancement of both fields.