The Air Quality Health Index (AQHI) is a 10-point scale that communicates the cumulative health risks associated with air pollution (ECCC, 2016). The general theme of this dissertation centers on an understanding of AQHI adoption while accounting for socioeconomic status (SES) in order to facilitate AQHI uptake by the public with particular focus on “at risk” populations (i.e. young children, seniors, and those with pre-existing respiratory and/or cardiovascular conditions). The study is unique since it approaches AQHI adoption consistent with the ecological model and an equity lens, and AQHI adoption is considered at the individual, organizational and community levels. The study area for this dissertation is Hamilton, Ontario, Canada. The findings from this dissertation contribute to an understanding of why AQHI is or is not being adopted and suggests potential intervention strategies to increase its uptake. Consistent with health behaviour theory, demographics (gender, age, education, area of residence), knowledge/understanding and individual risk perceptions (neighbourhood air effects on health) were found to be significant predictors of AQHI adoption. Additionally, perceived benefits of AQHI adoption included protection of health for self and those cared for via familial and/or occupational duties. While perceived barriers of AQHI adoption included lack of time required to check and follow AQHI health messages and the inability to “self-identify” as belonging to the “at risk” population. This dissertation proposes that increases in AQHI adoption may be achieved by increasing AQHI knowledge and emphasizing the benefits and relevance of AQHI such that “at risk” populations can self-identify. Additionally, AQHI uptake may be increased by providing AQHI information at a neighbourhood scale via local media sources and wearable devices. / Dissertation / Doctor of Philosophy (PhD)