如何把握观念史研究特别强调的观念起源、存在形式及其历史过程，知识社会学提供了一种重要的理论路径，其方法论上的操作基础就是探讨“观念的社会影响”“观念的生成机制”和“观念的群体意识”。作为一种被科学话语精心构筑的意指概念，PM2.5的“出场”意味着一场深刻的知识赋权行为，人们得以通过对PM2.5的识别来把握雾霾及其环境观念。然而，秸秆焚烧事件打破了城市话语和乡村话语长久以来的对话关系，PM2.5深层的话语实践和社会文化实践均呈现出明确的阶层属性。PM2.5议题分析过程提供了一种可供借鉴的观念史研究的修辞学方法路径，具体表现为对六大修辞命题——修辞资源、话语形式、框架形态、接合机制、修辞实践和阶层批判的识别和分析。

Sociology of knowledge, by examining the social impacts of ideas, the generation mechanism of ideas, and the group consciousness of ideas, provides a useful theoretical approach to the history of ideas, which emphasizes the origin, pattern, and historical process of ideas. As a type of ideographs elaborately constructed by scientific discourses, the emergence of PM2.5 symbolizes a far-reaching knowledge empowerment. It was through the identification of PM2.5 that people are able to recognize haze as well as the environmental idea. However, The Jie Gan Fen Shao Events (or Straws Burning Events) has undermined the dialogues between urban discourses and rural discourses. Both discursive practice and sociocultural practice of PM 2.5 present distinctive class attributes. This study provides a rhetorical approach to the history of ideas, including the identification and analysis of six rhetorical perspectives: rhetoric resources, discursive forms, frameworks, articulation, rhetoric practice, and class criticism.