With recent declines in air quality, the significance of urban green spaces and their ecological functions have rapidly increased, especially with regard to the reduction of particulate matter. Various investigations regarding particle reduction in urban green spaces have been conducted; however, specific guidelines to establish empirical data for green spaces and to inform related policies are still lacking. Thus, this study aims to categorize experts’ perceptions of green spaces through Q-methodology and to identify ways to form a consensus, establish policies in the design and construction process, ultimately aiming to enhance particle reduction effects in urban green spaces. As a result, experts’ perceptions were classified into three categories: ‘active support,’ ‘skeptical,’ and ‘passive support’ groups. Experts’ opinions on the particle reduction effects of urban green areas are overarchingly agreed upon; however, the priorities involved and methods used in augmenting green space integration require further analysis and mediation. Additionally, further empirical evidence should be accumulated on the particulate matter reduction effects of urban green areas, including the quantification of particle concentration reduction in urban green spaces and considerations for policy establishment in design and construction.